currently out of date as of September 2022, needs a fresh update
TLDR; edit the amdgpu-install script to add pop as supported debian distribution, comment out check for linux-modules-extra-[versions] since they're provided by linux-modules [per Jeremy Solle of System_76], then run with --no-dkms
3 EDIT: 4 things need to be done.
Problem 1) Pop!_OS not valid install target "Unsupported OS: /etc/os-release ID 'pop'" The issue as of now is that amdgpu-install doesnt recognize pop as a valid installation candidate. Solution is to add pop as a valid target in the amdgpu-install script.