jadsel

You might want to look into Snapper: https://documentation.suse.com/smart/systems-management/html/snapper-basic-concepts/index.html

Booting from snapshots has pulled my chestnuts out of the fire a few times--between using a rolling release distro as my daily driver, and NVIDIA graphics not always behaving well in conjunction with that.

If you install the Linux bootloader on the other drive with Linux, Windows basically just doesn't know or care that the it exists to bother writing over it. You can use UEFI to choose what to boot, but GRUB works fine with entries across different drives.

That said, it's not actually that hard to fix with a live USB if Windows does decide to eat GRUB on the same drive. I've been taking my chances on laptops particularly for years. So far, the only real problem I've run into was doing something stupid while dead tired and managing to nuke the Windows bootloader all on my own--somewhat ironically, while I was setting up another Linux distro to boot off a new drive! Which was also totally fixable, but a bigger pain than reinstalling GRUB would have been. (Especially with not being nearly as comfortable dealing with Windows stuff.)

I haven't seen anything really discouraging out of Infomaniak, either, for e-mail and drive services. Been using them for a while now.

As already commented, the vast majority of apps are fine with Graphene and its optional sandboxed Play Services. Mainly some banking apps can be tricky, but otherwise you're good. You can also use alternatives like Aurora Store rather than Google directly to get your existing apps which aren't on F-Droid; the only real exception there is paid ones.

I got a Pixel and made the switch over about a year ago, and it has been pretty smooth sailing. I also really do appreciate having full control over which permissions to allow each app. I know some people do prefer to run Google's stock camera app or keyboard, but it's easy enough to not give those network access to phone home.

You can. It's pretty configurable, as camera apps go. I switched because I wasn't entirely satisfied with the stock app, and haven't been disappointed so far.

Does it work if you launch steam through mangohud? Like:

mangohud steam-native

You would probably want to temporarily remove the per-game launch command while running it that way, for the HUD to actually show up in game (assuming it will load). But that's another approach to try, at least for troubleshooting purposes.