https://github.com/c1570/MrVSFUnfreeze
These scripts allow to convert a VICE VSF snapshot file to a C64 cartridge (CRT) file. While the cartridge content gets copied to the C64's RAM, the user can look at nice graphics supplied as a Koala file at build time.
MVU uses the Magic Desk (19) cartridge type. Hardware for it is readily available (e.g., c64-magic-desk-512k).
For crunching, MVU uses LZSA1 and 6502 decompressor code by John Brandwood.
The VSF unfreeze code is a modified version of VSFReanimator.
For building your own cartridge, you will need to adjust sources (file segments, compression, helper starting offset). The comments available in cartridge.asm might help a bit with that.