first of all for what it is good job i can't wait to see where this goes. My system's information is:
Quest 3 installed via Sidequest.
it loaded up fine i also had the floor issue. it seems when you use the in game reset position, it levels the floor to your head. i got around this by simply putting my head on the floor and hitting reset position. i would maybe recommend a manual "height" setting that lets you lower the floor.
I understand the logic behind hiding the cursor when the menu is closed. some peoples confusion is probably from clickable things still being visible and even highlightable when the menu is closed.
for a first time project, its honestly not that bad. keep up the good work.