What would be the best Free Software ("open source") game engine for procedural generation, not just of terrain, but also of models as a whole?

I love the works of Farbrausch and my ultimate goal in game development is to have a custom engine that procedurally generates all of its meshes at runtime, if only in a loading screen, using the power of modern GPUs. But for obvious reasons, the scope of that engine is beyond what I can use in a timely manner for a game. What existing FOSS program can best help me to both create, and learn about, procedural generation of 3D models? So far, Godot is not particularly helpful in this regard, and has limitations on this particular issue even in 4.

https://redd.it/15qaz75
@proceduralgeneration

designs from code

https://redd.it/15qmzho
@proceduralgeneration

Procedural stylized rugelach cookie | Houdini
https://redd.it/15qo70x
@proceduralgeneration

Different terrains with our improved vegetation generation.

https://redd.it/15qqe3z
@proceduralgeneration

[UPDATE | Train board generator] - Create custom Ticket to Ride boards within seconds!
https://www.reddit.com/gallery/15qqesz

https://redd.it/15qqja1
@proceduralgeneration