well, today i (partially) realized why my basic drivers don’t work: the preinstalled packages amdgpu and amdgpu-dkms seem to not work due to amdgpu-dkms being unconfigured. tried configuring it and got the same error. around about there my system stopped using even the iGPU and i had to uninstall some other drivers (thanks @lena@gregtech.eu )
Even ROCm on some distros isn’t that bad. On my 7900 XTX (admittedly an officially supported card, your mileage may vary on unofficial cards) on Fedora it was just a case of doing
sudo dnf install rocm-*
and everything installed (might be some extra packages you need after for specific apps, but you know if you need them). On openSUSE though, it was a total pain.