

My Linux PC is a media server/htpc with access to all codecs. I regularly transcode H.265 via nvenc for jellyfin.
You must ensure you’re using a client that can use the codec in question, regarding proprietary codecies like H.265 you will need either a desktop client that can handle it, or verify you have your browser properly configured.
Is there a specific codec you’re concerned about losing access to?
The arch wiki page here lists all the common video codecs as well as packages to install them, assuming you’re on an unlocked steam deck these packages will work, otherwise you’ll need to source them yourself.
Minecraft bedrock is only accessible on Linux through waydroid or other android emulators.
There’s a few other games in the mobile markets that are decent, I’m sure.