ESO players on Steam can now explore Tamriel using the portable Steam Deck! We are thrilled to announce that The Elder Scrolls Online now has “Playable” status on the Steam Deck. This means that Steam ESO players can now venture into Tamriel’s Second Era using the portable PC gaming device. Never miss a Daily Login Reward again! If you play on Steam and have a Steam Deck, simply find the game in your Library to begin the download.
Sounds like it — it was posted by The Elder Scrolls Online, not Valve. (Edit: Yes, of course this still means Proton.)