That's really great and quite conveniently timed for me I've been working on my own sky rendering over the last week or so of evenings[1], to end up as a Godot plugin and perhaps a writeup. It started as deep dissatisfaction with the results I could achieve with what was available. I'm still on the fence about the distance to go for realism vs whatever I find aesthetically pleasing.

https://www.youtube.com/watch?v=BJDgmVUL7HY

This paper was the point I jumped in with An analytic model for full spectral sky-dome radiance

https://dl.acm.org/doi/10.1145/2185520.2185591

The video you linked is currently private