In Desktop Mode there are plenty of free and open source games available, which can be manually added to Steam Launcher.
Great Thanks for your write Up. I would love the idea that Steam Deck comes preinstalled with an Open Source Game like Xonotic!
Yeah I mean I would totally understand if people in the Xonotic community felt weird about this, you can already download Xonotic off of flathub in 5 seconds on the deck, but regardless in my opinion it would be perfect as a fun open source game that came default on a gaming device like the deck.