None of these things are secrets or even hard to learn on one’s own.
I am not a developer (not a real one, anyway) and I am definitely not a game developer but I wrote a ton of 3D stuff for work and learned all of these optimization techniques along the way.
Once one learns the basics of how data is sent to GPUs, these techniques all become obvious, though some are much more difficult when you don’t restrict yourself to a world built with axis-aligned cubes.