SteamOS is not a good general purpose distribution for random PCs. Internationalization is basically non existent. For an external keyboard the layout is hardcoded to US in Game Mode and for people who don't know where to look it's basically impossible to find where to change it in Plasma/Desktop Mode. Language files including spell check dictionaries are unavailable for anything but English, presumably to save storage space everywhere for the 64GB Deck.
If you manually set the system language to anything but English, you end up with a weird mishmash of languages because the .desktop files still contain all translations, GUIs of bundled apps stay English, and Flatpak apps respect the language setting.
The sole thing SteamOS has over other distributions is the fact that you can order a Steam Deck and everything is already right there. Once installation on random PCs comes into play, SteamOS loses against Fedora and alike hands down because those have the wizards to set up language, encryption, dual boot, etc.
The biggest downside of Fairphone IMO is that they don't maintain their hardware support in LineageOS and for the retail product then branch development off, add a bit of custom branding and adapt whatever Google requires these days. It would greatly improve custom ROM support in general.
Sometimes last year Marquez Brownlee (I think it was him, I don't think it was Dave2D) was conducting a blind test among his audience which Photos they thought looked best. Some top brands were jumping up and down from one test scenario to another but the Fairphone ended up in the midfield constantly. True, that's not a glowing recommendation of the camera but at least an insurance that one doesn't get utter trash either.
Just get rid of everything Nvidia. Problem solved.