If the game loop doesn't run at the same speed as the render loop you'll get 'tearing' - some game objects are at the latest state, some are not.
That can cause some funky bugs.
Because it's easier to programm a single thread that executes a sequence of commands like [ update-gamelogic, update-graphics, etc. ] instead of at least 2 threads (for gamelogic and graphics) that you have to synchronize somehow. Synchronization can be pretty difficult!
Phones that run mainline Linux are seldom.
The only ones that come to my mind are PinePhone Pro (outdated hardware, 400 bucks) and Librem 5 (also outdated hardware, incredibly expensive 1300$ !).
If you are serious get the PinePhone Pro. But expect pitfalls because you can't just run Android apps.
Nextcloud is still the best option for self hosted cloud services.
You can just buy an aftermarket anti-glare screen. They are cheap.
You can change the SSD by yourself but you'll lose waranty. There's a noticeable speed difference between the eMMC and NVMe versions. There's no noticeable speed difference between the NVMe versions.
IMHO if can afford it and have a few technical skills buy the little one and install one of these. You might even want to wrap it in one these (there's a real leather option too) or these or replace the joysticks with these (can't get drift and have a much smaller deadzone).
I recommend Fire Emblem: Three Houses.
It's a tactical role playing game which means you have a bunch of characters that you level up in and outside of tactical battles.
Maybe you like it.