I appreciate you making a 3D game in Godot in a short time, I wanted give some tips I figured out myself that you may already know. The UI doesn't scale to Fullscreen, you can fix this in the project settings for window and change "Mode" to (canvas_items) and "Aspect" to (keep). For exporting to web, the game will lag when you turn the camera around the first time because the environment is getting unculled for the first time, you can black out the screen and turn the camera around for a couple frames before the game starts and it won't stutter while playing.