For Epic Games, I'd also recommend Heroic. You can download it from the Discover Software Center in Desktop Mode.

Some quick tips:

• If you need to bring up a keyboard for whatever reason, you can hold the STEAM button, and press X.
• Expect to tinker and play around with things, I think the software is still a bit new and rough around the edges.
• Search the Discover Software Center for software in general; it's a good place to download things like browsers and applications.
• If you want to know if a game runs or not, you can check https://www.protondb.com , it's a crowdsourced version of Valve's "Steam Deck Verified", where people say how well games work.

Some game recommendations, based on ones I've played. Not had a chance to try them all on the Steam deck, but they should work:

• Stardew Valley
• Baba is You
• Celeste
• Cuphead
• Dicey Dungeons
• Slay the Spire (Think you have to use the touch screen though)
• Sonic Mania
• Wargroove
• Zeepkist
• The Binding of Isaac: Rebirth
• Hades
• Pizza Tower
• Tunic
• Return of the Obra Dinn
• Demon's Tilt