Agree with a lot of this I also wanted to suggest a few things but seems like you got most of what I wanted to say covered and a ton more. I can see buying a polished version of this game that plays like Downwell. Keep the GBA artsyle and color palette, add more biomes, more enemies, more upgrades (for example upgrades that incetivize jumping over normal skating and vice versa), more interactable enviroments (like rails for the skate), more modes (infinite mode, story/arcade, or lean on the roguelike aspect and make it a full game like that).
Man this game is great I can see it going a lot of ways all of them good real props to the devs.