- `radeon` is in the box (for Fedora, I assume Ubuntu) and has worked on half a dozen different cards over the last decade. I've never installed `amdgpu` but it looks no more difficult than nVidia's proprietary drivers?
- Thunderbolt is a continuing problem, though TB3 is significantly improved IME. Docks and multi-monitor over DisplayPort MST are fine. Haven't tried PCIe extensions.
- Many-buttoned mice work better than they do on Macs, I'll tell you that much.
I bought a WiFi + Bluetooth PCIe card last month; it was one of those cheap Chinese no-brand cards that consist in an Intel WiFi chip slapped on a board. It worked instantly without installing anything, with just the drivers shipped in the Linux source tree that every distribution has. My mouse is a Logitech mouse with 5 buttons and it too works out of the box.
How long has it passed since the last time you installed Linux? It has changed a lot in the last 10 years; lots of things work flawlessly now. I haven't had to meddle with any driver since at least 2010, when my shitty ATi Radeon X1600 still only worked under FGLRX or when I tried to use a crappy Chinese WiFi dongle whose drivers were only distributed as source on a CD (damn you realtek)