On amd gpu+cpu fastboot off. I have it working on 3 pc’s like this. Asus mostly.

Use steam, setup a desktop profile in settings while in desktop. https://docs.bazzite.gg/Handheld_and_HTPC_edition/Handheld_Wiki/ search for desktop controls.

It is 90% arch, except for the few packages it has in it’s own repository. I have it on two pc’s and I have used arch for years I can not say it’s any different from a stability perspective. I almost never have issues on arch but also I wouldn’t recommend cachyos to anyone who had issues with arch. Couse I definitely had to remove custom packages just to fix dependency issues etc.

Yes it is that, on gentoo I had set it like that for a while. Before I specified it to be sure. I Thought linus, didn’t want to have this.

Yes, most likely need to compile it yourself. Or the distros would need a v1,v2,v3,v4 version. Also you need to know the feature set of you cpu. Distros will probably compile with the lowest common denominator, since those are compatible largest range of cpu’s. Cachyos does compile it’s packages for v3 optimization, I don’t think that needs avx512. So can definitely see some distros trying something out.

You can start the restore/factory reset from the phone. But if you need iTunes after, then you probably have to run windows in a vm like qemu. Also might want to pass trough ‘usb hub’ to that wm. Wich if the usb controller share several ports you would want to use mouse and kb on different usb-controller.

Cachyos, since I like archlinux and the things it comes with I would install on arch. There’s even a few things that would have to be compiled from aur that’s in their repository pre-compiled.