The puzzles are pretty fun and well designed! I like how the collectibles allow the player to determine their own difficulty.
Though I would prefer to be able to iterate more quickly as you often need trial and error to determine how far a given command will get you. So maybe the commands could be executed faster, and also there could be a way to start faster (e.g. press Space) instead of having to drag your mouse over to the tiny start button every time. A reset commands button would also help a lot, alongside a more generous dragging area as sometimes the blocks end up snapping back to the stack. Oh and also restarting the level shouldn't reset the commands but pretty sure that's due to time constraints.
Quality of life features aside, it's pretty cool! A classic game jam trope of programming characters, executed nicely. Well done!