Today at the grocery store a sweet older lady approached me and asked if I knew anything about computers. I said yes I do, and she produced a mouse saying that her son set up Linux mint for her and she was wondering if the mouse was compatible. It needed kernel version 2.6 or newer so I said that the mouse should work, guessing mint itself was probably newer than that kernel. Happy with my answer, we chatted a little, then she thanked me and left.
It was a nice experience, so I thought I should share!
My experience is still a good success rate there. Back in ~2015 my family got an USB WiFi card which needed an out-of-tree module, which the manufacturer had on Github, complete with DKMS instructions. It was upstreamed after about a year, though!
The only completely unsupported device I've had is my laptop's fingerprint sensor.
I'm afraid that's not true. Attempting to use an NVIDIA GPU will cause problems. You can kinda-sorta mitigate some of them, kinda-sorta, but not really, and the web is filled with people complaining about said problems.
I think it's gotten better in recent years. Years ago when I was trying to switch to Linux I had an NVIDIA 750 GTX Ti, back when it was the first Ti card and required the absolute latest drivers. Ubuntu's repos didn't package those drivers and Nouveau didn't support it, so I had no choice but to install NVIDIA's drivers manually. Then every time the kernel updated the drivers were effectively uninstalled and my system was unusable until I reinstalled the drivers manually. That experience led me to switch to AMD for the next card I bought.
About a year ago though I switched back to NVIDIA for the AI capabilities and I've had an absolute flawless experience with it, despite using (or because of?) Arch.