mario galaxy character controller with faux gravity

Hello there ! after searching, reading, and trying different approaches, I can' get a capsule walking on a spheroid (deformed "terrain"like sphere) and climbing slopes, following the planet gravity.

Using a very good example in theFaux gravity post I understood how to make something walk on a perfect sphere, but that doesn't work with a complex terrain, or any other object supposed to be climbable. I tried putting together a WASD rigidbody movement script, but it keeps on giving me the same issues. so, basically doing a step backward, and reconsidering using bundled character controllers: any advice on how to make a character walk on a complex surface with an arbitrary gravity center ?

thank you so much for ideas/brainstorm/answers !