A C++ ray tracer from scratch was the course project for my computer graphics class in 2016. I enjoyed the exercise immensely. Not nearly as robust as yours of course.

I basically was ready to come on and make a snarky comment like this. "I wrote one in the '90s!".

and then I saw the examples, and the feature set. I particularly like the blender-to-Luz export.

It seems great. Good luck to OP.