Really good puzzle design and mechanics, and there's a lot of content for a game jam entry! I really like how the latter puzzle designs mix up when you want to hold onto blocks with the magnet and when you don't. The retro Game Boy aesthetic is also really well done and the visuals area really easy to read. The current difficulty is pretty good I feel and it would be interesting to increase the difficulty via either additional mechanics.
I think with the current set of mechanics, one thing to explore is levels that require you to have magnets attaching other magnets (IIRC none of the current levels have that?)