What a great-looking pico-8 game! As a novice pico developer myself, I don't feel qualified to critique the graphics, but there are a lot of impressive effects in here that look fantastic.
You weren't kidding about the difficulty. I definitely appreciate the challenge and was totally hooked for quite a while! I do wish that there were a few quality-of-life improvements: the ability to peek forward at upcoming terrain, and a togglable "grid" so I can see exactly how far away my character is from a given ledge or jump. It was a little frustrating to have to memorize the sequence of moves to get to an offscreen checkpoint since you can't actually see the screen where you previously died while planning your next move.
I do really like a lot of the game decisions you made here - forcing the player to play all four of a random card set (with one permitted reshuffle) created a lot of delicious, organic puzzles that aren't easily brute-forced by trial and error.
I have no complaints about the UI - and it's impressive that you created such an unintrusive series of menus and icons that are intuitive to the player without a lot of aggressive tutorials or onscreen text.