Wine is the compatibility layer that allows you to run games and applications developed for Windows - on Linux (plus also macOS and BSD). It's a major part of what makes up Steam Play Proton and enables a ton of games to work on the Steam Deck.
Project Zomboid, a survival game from The Indie Stone that's currently in Early Access just had a big new stable release, and it should now work better on the Steam Deck and with controllers overall.
Old World is a new Native Linux historical strategy game from Soren Johnson, Lead Designer of Civilization IV and Offworld Trading Company and Mohawk Games.
With the big Sentinel update to Path of Exile out now, I gave it a spin on my Steam Deck to get a feel for the controls and it really does work nicely.
After not hearing much from Cradle Games and tinyBuild on Hellpoint, they've now announced the first major expansion Hellpoint: Blue Sun releases on July 12th. This is along with console next-gen stuff.
Songs of Conquest is a brand new release from Lavapotion and Coffee Stain Publishing, a turn-based tactical RPG with kingdom management that definitely feels like Heroes of Might and Magic.
Originally Amazon Lumberyard that was donated to open source, the Open 3D Foundation just announced a big new release and they have an annual conference coming up.
The Garden Path is an upcoming casual chilled-out life sim that looks gorgeous. Now you can get access to it with the early bird limited access system on itch.io.
Another absolutely huge update for the Steam Deck just landed, with Valve clearly taking on lots of feedback to make it the best handheld gaming device around.
In a nice big win for open source, NVIDIA has today officially revealed that they've released open source Linux GPU kernel modules. Additionally, driver version 515.43.04 is out.