Humble Store just launched a dedicated Handheld Friendly Sale.
They don’t include any ratings for Steam Deck, they just seem to have stuck a whole bunch on sale so I’ve gone through and picked out a bunch for you that you might like along with the Deck Verified and ProtonDB ratings for desktop gamers to save you some extra clicking around.
Streets of Rogue - 75% off - Deck Playable / Linux Native
Devil May Cry 5 + Vergil - 67% off - Deck Verified / ProtonDB Gold