[chupasaurus]

tl;dr: AMD - if a particular GPU is supported by your kernel and Mesa versions, it works flawlessly, NVIDIA - way more ifs and randomness.

AMD: check in which kernel version AMD added the support for your GPU, and which Mesa version has feature parity (most of the time it's already there because there weren't any big shifts since Vega, RDNA2 might be that one) and you're good to go on any distro.

NVIDIA: Wayland support isn't there for years and foreseeable future, random issues with driver updates. Supports only 3 distros (Red Hat family, SUSE and Ubuntu without derivatives, I even made a page for devs how to add Debian flavour of it on any deb distro since Mint users were constantly struggling), Debian makes it's own decoupling of blob which works flawlessly but new version might not be there for a month because maintainers aren't there. I still remember that full support for Pascal has landed 6 months after the release.