SteamOS the operative system will always be supported but as of today there are no other officialy released devices with SteamOS other the Valve's Steam Deck lineup.
It is working, but the user experience might not be that great it as we want it to be just yet.
You will also need to manually configure the input to match your desktop and might need to tweak more settings. If you want to try it make sure that your distribution has flatpak support (else you will need to install it).
ARM devices are not supported currently. ES-DE does support the ARM emulators but it is a very different landscape.
It would be a major undertaking but maybe one day in the far off future it could be possible. But it would need to be a different experience as the emulators, other underlying systems would not be the same and would need to be rewritten.
But the team is not large enough to migrate and maintain other distribution methods, so we prefer to focus our effort on Flatpak only.
If someone with the knowlage and passion wishes to help us with migrating to a solution and help us maintain it, we are open for discussion it at least.