On UI frameworks... mostly agree, I say this as a COSMIC user even... so many apps still don't show up right in the tray, but it's getting a bit better, I always found KDE to be noisy, and don't like how overtly political the Gnome guys are. So far Wayland hasn't been bad, X apps pretty much just work, even if they don't scale right.

I'm on a very large OLED 3440x1440 display and haven't had too many issues... some apps seem to just drop out, I'm not sure if they are on a different workspace or something as I tend to just stick to single screen, single display. I need to take the time to tweak my hotkeys for window pinning. I'll usually have my browser to half the screen and my editor and terminal on the other half... sometimes stretching the editor to 2/3 covering part of the browser. I'm usually zoomed in 25-30% in my editor and browser... I'd scale the UI 25% directly, like on windows or mac, but you're right it's worse.

For webcams, I don't use anything too advanced, but the Nexigo cams I've been using lately have been working very well... they're the least painful part of my setup, and even though I tend to use a BT headset, I use the webcam mic as switching in and out of stereo/mono mode for the headset mic doesn't always work right in Linux.

On audio filtering, I can only imagine... though would assume it's finally starting to get better with whatever the current standard is (pipewire?), which from what I understand is closer to what mac's interfaces are. I know a few audio guys and they hate Windows and mostly are shy to even consider Linux.