I get that it won’t be turnkey like in Windows

actually, for my vive, the setup was EASIER than on windows as steam does all the heavy lifting and I didn't need to install the vive software, and didn't have to pair my controllers, room setup is simple same as windows.

Just so we are clear, you are able to play Steam PCVR games and use the SteamVR environments

I only do pcvr, and the steam overlay works for LOOKING at your desktop (sadly can't interact with desktop through steam, it just closes, but there is an easy to install app that is kind of like Desktop+ that gives desktop control with a double press of a button on your controller) or using the steam launcher. I stopped using their environments (I had the basic and some Dr Who ones, some star wars ones like the cantina and millennium falcon) on my older pc cause the environment was adversely affecting performance(don't think it was shutting off completely, I now simply use the empty space on the round grid with mountains in the distance and bring up my steam menu from the controller.

I just use ‘Virtual Desktop’ for streaming 100% of my PCVR content to a Quest 3 wirelessly

I never used VD and the people I know that do are only on windows.

I assume handling the controllers and telemetry is all software for Steam and not needing obscure system calls or api’s that will have driver complications?

I wish I had an answer for this one. Can quest use the steam backend like vive/index? if so should be good. I know vive and valve worked together on the software so are compatible that way. Like I said above wrt controllers they just worked with no pairing, both my index controllers and vive wands (I did a quick test for someone who was having issues with vive wands "stuck on the floor while in their hand"

Just make sure you use the steam installer from the steam site, not the flat pack or snap or whatever, they don't have the correct screen lease thing (whatever it is called) and I used Kubuntu simply because when I started my journey KDE was the preferred DE, I personally prefer Gnome but VR dammit, and wayland was the better choice for VR x11 maybe better now for VR but wayland is the future from what I read.