How do I use a <Plug> as a keymap group prefix?

[kshenoy]

I'd like to do the same thing as the example in the helpdoc:

    wk.add({
      { "<leader>f", group = "file" }, -- group
      { "<leader>ff", "<cmd>Telescope find_files<cr>", desc = "Find File", mode = "n" },

However, I want to abstract away what I want to use as a prefix using a plug. This is my code today:

vim.keymap.set('n', '<Leader>f', '<Plug>(leader-file-map)',  {remap=true, silent=true, desc="Files..."})
vim.keymap.set('n', '<Plug>(leader-file-map)f', telescope.buffers, {desc="Find file"})

I'm not able to figure out how to communicate this to which-key