Nice submission! I really like the simplicity and the 3D scene. You're just flying around a sphere, but it looks really immersive.
I guess we're in the same 'please download if you have performance isssues'-club. We also did a 3D submission and struggle in making it browser-friendly... We also couldn't figure out how to capture/hide the mouse properly. I hope the godot-support will get better in the future!
Despite the known 3D-browser-issues your game works suprisingly well in my firefox 103.0.2 (64bit).
You could make the 'start'-button clickable, too, so no keyboard interaction is necessary at all.