Maybe have a circle in the center of the screen where the mouse can go anywhere in there but if it goes outside of the circle, it goes back to the center of the screen (the cursor does). Example:
Viewing post in The Journey of Mr Hughes comments
Also it may seem like im the only one who cares about this right now, but if you share this with relatives, friends, etc it *will* help this gain attention. Your game is a hidden gem hiding in some ball pit of bad games (yours isn't). Does that analogy even work? lol idk Anyways keep up the great work!
P.S. Is unity personal complicated in terms of UI? Or is it easy for a complete beginner to understand