How usable are other Linux distros?

[kl8n2k5]

Losing settings and pacman packages every update is annoying, so I'm considering maybe straight Arch like I've got on my desktop. Would I be losing much functionality? I don't care about "Gaming Mode" but I wanna be sure I'd still be able to have controller support and the on screen keyboard.
EDIT: Should've thought to check the wiki (the whole reason I like this distro lmao) since they actually have a page specifically for this: https://wiki.archlinux.org/title/Steam_Deck

[Mahjik]

You could check out Bazzite:

https://bazzite.gg/

[Haruspex]

Controller support will just be dependent on Steam being installed, so any distro will work there.

Most of the SteamOS alternative distros aiming to replicate the functionality of SteamOS like Bazzite, HoloISO, and Chimera OS also feature the immutable base system, which you don't want if you're trying to use Pacman packages and such. With these, the intent is to embrace Flatpaks and containerization, which personally I think is the future of the Linux desktop for normies.

There is a Steam Deck or HTPC specific version of Nobara Linux[nobaraproject.org], but it's Fedora based and if you're very insistent on using the Pacman package manager, you're going to want something Arch based.

I mean, if you really use Arch BTW, you can just roll your own and do what you want. Install the desktop environment you prefer, install Steam, and install whatever on-screen keyboard you desire from wherever. Most people using the Steam Deck enjoy the more console-like feel of not having to do any of that though, but you can do what you prefer.

[Mahjik]

To Haruspex's point, if you are already familiar with various distributions then you know anything you do isn't permanent. i.e. you don't find anything you like just reinstall SteamOS.

You never mentioned with Deck you have, but I think the challenge with some of the other distros is WiFi on the OLED. No all drivers are pushed from Valve to other distros. I haven't heard of anyone having difficulty with the LCD model.