I felt the itch to play Diablo 2 again so I went and installed Battle.net in Heroic. It failed with Heroic’s "Proton GE (latest) " (whatever that means) but it worked with Proton GE 10.25.
Anyways, it opened the game list already with a filter for “Handheld” applied to only offer me games that work well on a handheld.
The funny thing is that I’m not even running SteamOS but OpenSUSE. But still Wine apparently gave the launcher enough info that it knew I’m on a handheld.
Would anyone care to test this out on a desktop PC? Maybe they equate Wine or Proton with the Deck. But I doubt it, I guess it went by processor or GPU.
Anyways, looks like Blizzard’s unofficial but working Linux support seems to still be a thing.
Proton is Valve’s specific fork of Wine. The launcher sees you using Proton while detecting controller buttons and then connecting that you’re on a Linux handheld.
Probably the combination of having a controller and touchscreen but NOT having a keyboard. Or recognizing the CPU series (SoC type). Or both.