Almost got it linking...

.gitmodules

@@ -16,3 +16,12 @@
 [submodule "Vendor/speexdsp"]
 	path = Vendor/speexdsp
 	url = https://github.com/xiph/speexdsp.git
+[submodule "Vendor/opusfile"]
+	path = Vendor/opusfile
+	url = https://github.com/xiph/opusfile.git
+[submodule "Vendor/ogg"]
+	path = Vendor/ogg
+	url = https://github.com/xiph/ogg.git
+[submodule "Vendor/opus"]
+	path = Vendor/opus
+	url = https://github.com/xiph/opus.git

Other Sources/ADBToolkit/ADBAppKitVersionHelpers.h

@@ -46,6 +46,10 @@
 #define NSAppKitVersionNumber10_8 1187
 #endif
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 BOOL isRunningOnLeopard(void);
 BOOL isRunningOnSnowLeopard(void);
 BOOL isRunningOnLion(void);
@@ -57,3 +61,6 @@ BOOL isRunningOnLionOrAbove(void);
 BOOL isRunningOnMountainLionOrAbove(void);
 BOOL isRunningOnMavericksOrAbove(void);
 
+#ifdef __cplusplus
+}
+#endif

Other Sources/Overrides/opus/Archs/celt.c

@@ -0,0 +1,16 @@
+//
+//  celt.c
+//  opus_boxer
+//
+//  Created by C.W. Betts on 10/14/23.
+//
+
+#ifdef __x86_64__
+#include "celt/x86/celt_lpc_sse4_1.c"
+#include "celt/x86/pitch_sse4_1.c"
+#include "celt/x86/vq_sse2.c"
+#include "celt/x86/pitch_sse2.c"
+#elif defined(__aarch64__)
+#include "celt/arm/pitch_neon_intr.c"
+#include "celt/arm/celt_neon_intr.c"
+#endif

Other Sources/Overrides/opus/Archs/silk.c

@@ -0,0 +1,20 @@
+//
+//  silk.c
+//  opus_boxer
+//
+//  Created by C.W. Betts on 10/14/23.
+//
+
+#ifdef __x86_64__
+#include "silk/x86/NSQ_sse4_1.c"
+#include "silk/x86/NSQ_del_dec_sse4_1.c"
+#include "silk/x86/VAD_sse4_1.c"
+#include "silk/x86/VQ_WMat_EC_sse4_1.c"
+#include "silk/fixed/x86/vector_ops_FIX_sse4_1.c"
+#include "silk/fixed/x86/burg_modified_FIX_sse4_1.c"
+#elif defined(__aarch64__)
+#include "silk/arm/biquad_alt_neon_intr.c"
+#include "silk/arm/NSQ_neon.c"
+#include "silk/arm/LPC_inv_pred_gain_neon_intr.c"
+#include "silk/arm/NSQ_del_dec_neon_intr.c"
+#endif

Vendor/libpng/CMakeLists.txt

@@ -0,0 +1,202 @@
+# selectively extracted and adapted from the libpng CMakeLists.txt, which has the following copyright notice:
+
+
+# Copyright (C) 2018 Cosmin Truta
+# Copyright (C) 2007,2009-2018 Glenn Randers-Pehrson
+# Written by Christian Ehrlicher, 2007
+# Revised by Roger Lowman, 2009-2010
+# Revised by Clifford Yapp, 2011-2012,2017
+# Revised by Roger Leigh, 2016
+# Revised by Andreas Franek, 2016
+# Revised by Sam Serrels, 2017
+# Revised by Vadim Barkov, 2017
+# Revised by Vicky Pfau, 2018
+# Revised by Cameron Cawley, 2018
+# Revised by Cosmin Truta, 2018
+# Revised by Kyle Bentley, 2018
+
+# This code is released under the libpng license.
+# For conditions of distribution and use, see the disclaimer
+# and license in png.h
+
+
+
+add_library(png STATIC
+  png.c
+  pngerror.c
+  pngget.c
+  pngmem.c
+  pngpread.c
+  pngread.c
+  pngrio.c
+  pngrtran.c
+  pngrutil.c
+  pngset.c
+  pngtrans.c
+  pngwio.c
+  pngwrite.c
+  pngwtran.c
+  pngwutil.c
+)
+
+option(PNG_HARDWARE_OPTIMIZATIONS "Enable hardware optimizations for libpng" OFF)
+
+if(PNG_HARDWARE_OPTIMIZATIONS)
+
+  message(STATUS "CMAKE_SYSTEM_PROCESSOR: ${CMAKE_SYSTEM_PROCESSOR}")
+
+  # set definitions and sources for arm
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
+    CMAKE_SYSTEM_PROCESSOR MATCHES "^aarch64")
+    set(PNG_ARM_NEON_POSSIBLE_VALUES check on off)
+    set(PNG_ARM_NEON "check" CACHE STRING "Enable ARM NEON optimizations:
+       check: (default) use internal checking code;
+       off: disable the optimizations;
+       on: turn on unconditionally.")
+    set_property(CACHE PNG_ARM_NEON PROPERTY STRINGS
+       ${PNG_ARM_NEON_POSSIBLE_VALUES})
+    list(FIND PNG_ARM_NEON_POSSIBLE_VALUES ${PNG_ARM_NEON} index)
+    if(index EQUAL -1)
+      message(FATAL_ERROR
+              "PNG_ARM_NEON must be one of [${PNG_ARM_NEON_POSSIBLE_VALUES}]")
+    elseif(NOT ${PNG_ARM_NEON} STREQUAL "off")
+      target_sources(png PRIVATE
+        arm/arm_init.c
+        arm/filter_neon.S
+        arm/filter_neon_intrinsics.c
+        arm/palette_neon_intrinsics.c)
+
+      if(${PNG_ARM_NEON} STREQUAL "on")
+        target_compile_definitions(png PUBLIC -DPNG_ARM_NEON_OPT=2)
+      elseif(${PNG_ARM_NEON} STREQUAL "check")
+        target_compile_definitions(png PUBLIC -DPNG_ARM_NEON_CHECK_SUPPORTED)
+      endif()
+    else()
+      target_compile_definitions(png PUBLIC -DPNG_ARM_NEON_OPT=0)
+    endif()
+  endif()
+
+  # set definitions and sources for powerpc
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "^powerpc*" OR
+     CMAKE_SYSTEM_PROCESSOR MATCHES "^ppc64*")
+    set(PNG_POWERPC_VSX_POSSIBLE_VALUES on off)
+    set(PNG_POWERPC_VSX "on" CACHE STRING "Enable POWERPC VSX optimizations:
+       off: disable the optimizations.")
+    set_property(CACHE PNG_POWERPC_VSX PROPERTY STRINGS
+       ${PNG_POWERPC_VSX_POSSIBLE_VALUES})
+    list(FIND PNG_POWERPC_VSX_POSSIBLE_VALUES ${PNG_POWERPC_VSX} index)
+    if(index EQUAL -1)
+      message(FATAL_ERROR
+              "PNG_POWERPC_VSX must be one of [${PNG_POWERPC_VSX_POSSIBLE_VALUES}]")
+    elseif(NOT ${PNG_POWERPC_VSX} STREQUAL "off")
+      target_sources(png PRIVATE
+        powerpc/powerpc_init.c
+        powerpc/filter_vsx_intrinsics.c)
+      if(${PNG_POWERPC_VSX} STREQUAL "on")
+        target_compile_definitions(png PUBLIC -DPNG_POWERPC_VSX_OPT=2)
+      endif()
+    else()
+      target_compile_definitions(png PUBLIC -DPNG_POWERPC_VSX_OPT=0)
+    endif()
+  endif()
+
+  # set definitions and sources for intel
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "^i?86" OR
+     CMAKE_SYSTEM_PROCESSOR MATCHES "^x86_64*")
+    set(PNG_INTEL_SSE_POSSIBLE_VALUES on off)
+    set(PNG_INTEL_SSE "on" CACHE STRING "Enable INTEL_SSE optimizations:
+       off: disable the optimizations")
+    set_property(CACHE PNG_INTEL_SSE PROPERTY STRINGS
+       ${PNG_INTEL_SSE_POSSIBLE_VALUES})
+    list(FIND PNG_INTEL_SSE_POSSIBLE_VALUES ${PNG_INTEL_SSE} index)
+    if(index EQUAL -1)
+      message(FATAL_ERROR
+              "PNG_INTEL_SSE must be one of [${PNG_INTEL_SSE_POSSIBLE_VALUES}]")
+    elseif(NOT ${PNG_INTEL_SSE} STREQUAL "off")
+      target_sources(png PRIVATE
+        intel/intel_init.c
+        intel/filter_sse2_intrinsics.c)
+      if(${PNG_INTEL_SSE} STREQUAL "on")
+        target_compile_definitions(png PUBLIC -DPNG_INTEL_SSE_OPT=1)
+      endif()
+    else()
+      target_compile_definitions(png PUBLIC -DPNG_INTEL_SSE_OPT=0)
+    endif()
+  endif()
+
+  # set definitions and sources for MIPS
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "mipsel*" OR
+     CMAKE_SYSTEM_PROCESSOR MATCHES "mips64el*")
+    set(PNG_MIPS_MSA_POSSIBLE_VALUES on off)
+    set(PNG_MIPS_MSA "on" CACHE STRING "Enable MIPS_MSA optimizations:
+       off: disable the optimizations")
+    set_property(CACHE PNG_MIPS_MSA PROPERTY STRINGS
+       ${PNG_MIPS_MSA_POSSIBLE_VALUES})
+    list(FIND PNG_MIPS_MSA_POSSIBLE_VALUES ${PNG_MIPS_MSA} index)
+    if(index EQUAL -1)
+      message(FATAL_ERROR
+              "PNG_MIPS_MSA must be one of [${PNG_MIPS_MSA_POSSIBLE_VALUES}]")
+    elseif(NOT ${PNG_MIPS_MSA} STREQUAL "off")
+      target_sources(png PRIVATE
+        mips/mips_init.c
+        mips/filter_msa_intrinsics.c)
+      if(${PNG_MIPS_MSA} STREQUAL "on")
+        target_compile_definitions(png PUBLIC -DPNG_MIPS_MSA_OPT=2)
+      endif()
+    else()
+      target_compile_definitions(png PUBLIC -DPNG_MIPS_MSA_OPT=0)
+    endif()
+  endif()
+
+else(PNG_HARDWARE_OPTIMIZATIONS)
+
+  # set definitions and sources for arm
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "^arm" OR
+     CMAKE_SYSTEM_PROCESSOR MATCHES "^aarch64")
+    target_compile_definitions(png PUBLIC -DPNG_ARM_NEON_OPT=0)
+  endif()
+
+  # set definitions and sources for powerpc
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "^powerpc*" OR
+     CMAKE_SYSTEM_PROCESSOR MATCHES "^ppc64*")
+    target_compile_definitions(png PUBLIC -DPNG_POWERPC_VSX_OPT=0)
+  endif()
+
+  # set definitions and sources for intel
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "^i?86" OR
+     CMAKE_SYSTEM_PROCESSOR MATCHES "^x86_64*")
+    target_compile_definitions(png PUBLIC -DPNG_INTEL_SSE_OPT=0)
+  endif()
+
+  # set definitions and sources for MIPS
+  if(CMAKE_SYSTEM_PROCESSOR MATCHES "mipsel*" OR
+     CMAKE_SYSTEM_PROCESSOR MATCHES "mips64el*")
+    target_compile_definitions(png PUBLIC -DPNG_MIPS_MSA_OPT=0)
+  endif()
+
+endif(PNG_HARDWARE_OPTIMIZATIONS)
+
+target_sources(png PRIVATE
+  # public headers
+  png.h
+  pngconf.h
+  pnglibconf.h
+
+  # private headers
+  pngpriv.h
+  pngdebug.h
+  pnginfo.h
+  pngstruct.h
+)
+
+target_include_directories(png PUBLIC
+  ${CMAKE_CURRENT_SOURCE_DIR}
+)
+
+target_link_libraries(png PUBLIC ZLIB::ZLIB)
+
+if(NOT MSVC)
+  target_compile_options(png PRIVATE
+    -Wno-self-assign
+  )
+endif()