I feel like diving or fishing has potential for local cozy coop (+ maybe online multiplayer). Something like this rather quickly gets a bunch of unique fish and a very interesting look.
Something with running a “lemonade stall” kind of thing always feels cozy and contained and small.
Or maybe fishing, diving, mining.
In general, I think a cozy incremental game could do quite well if I make that. They are “programmer” games. They don’t need a lot of art or good art; just very interesting systems and numbers.
Or like a “small management” game, inspired by things like “Minami Lane” or Boba Simulator
This is another example of how effective a simple cozy game can be: https://store.steampowered.com/app/4417620/Good_Catch/