If you rotate the hinge to angle X above the horizon, light coming in from an altitude angle of 2X (=zenith angle of 90deg-2X) will get reflected to into horizontal rays inside the tube.

So you don’t need a mount with adjustable altitude angle - the hinge accomplishes that.

There are a few typst packages for making presentation slides. Which one did you use?

No love for GNU IceCat?

Looks nice! Is this yours (OP)? If so, are you aware of Bavarder? It seems to have quite some features. (But it is unmaintained and broken right now so Alpaca is a welcome replacement.)