[__aru]

because official SteamOS doesn't support the Xbox Ally X yet. It's safe to assume that official SteamOS will eventually support the Xbox Ally X, but it's not there yet.

Valve moves slowly to add support for more devices, etc, whereas the Bazzite devs can move faster.

e.g.

Bazzite does a weekly release of a stable OS candidate, whereas Valve often takes months, if not up to a year, for to release a stable-channel OS update.

Edit:

Also, Valve tends to wait for proper kernel interfaces for functionality like controlling TDP, RGB, fans, etc. Whereas Bazzite devs are fine with using tools in userspace to directly talk to hardware, etc.

While I do think Valve's approach is better for long-term maintainability, Bazzite will always have the speed advantage because it can hack together a solution via userspace applications.