I tested both on Steam Deck and VOMP certainly works better on the platform since Beat 'Em Up just have easier controls and we supported Xbox gamepad anyway.
For Dwarven Skykeep controls include both keyboard and mouse and while playable from touchpads it's far from perfect. Though it's the one made in Godot and it took us 3+ years to build. :-)
Do you recommend I start with Dwarven Skykeep or Vengence of Mr. Peppermint if I'm playing on a Steam Deck?