I tried this out, I was unable to log in with Firefox or Chromium. It appears the only games that it supports in this alpha are Stardew Valley and Cyberpunk 2077. I have Stardew Valley installed and it finds it.
It’s a good start, though. I hope this gets updated soon.
UPDATE:
Santiago Santiago has updated a video on how to install Fallout: London on Steam Deck.
YouTube
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