ill reply to your bullet points:
1 and 3 and 7 and Gameplay: My main goal was to ease players into the mechanics, so verticality is introduced later into the game. I've gotten this comment a lot and the use of 3d seems to have annoyed you, I request you please play the entire game as multiple levels utilize 3D.
4: I get this, I may re-word the tutorial... Making all pushables completely brown will not work. You can only push the brown part of a pushable object, a mechanic I will expand on later.
5: I may add an animation to using a terminal, having the camera auto-move near any terminal may be jarring.
6: Ill look into adding a visual grid. However, the undo button should help get anything unstuck for now.
7: I actually only use checkpoints a few times. They were used when the movement was really early and bad. Their main use now is just a place to undo to.
8: Interactable signs are a great idea. Ill look into implementing them.
Gameplay: I may make the tutorial skippable if it is redundant, leaving it in for players who may need it... Everyone does keybinds differently.
Final note: Due to some interactions, the objects are prisms. Without spoiling anything, world 2 introduces a mechanic that differentiates them.