On the upside, this discussion has made me realise that there isn't actually any aspect of the games existing grappling rules that I do like, so I can remove them wholesale and start from scratch. Which is nice.
Welcome to my world.
At the start of this thread, this was what I was thinking.
Ok, so assuming you were starting from scratch, what would your solution look like?
No idea how to translate my notepad into text, but it's basically a branching tree currently. So you inflict [X], which opens up options A, B, and C. Those could be do and done effects, ending the grapple (EX: Half Action: Grab, Half Action: Throw) or set up effects that open up new choices of their own (Grab -> Takedown -> Arm / Knee bar). It's pretty raw notes at this stage though. I want to have a large number of common grappling techniques represented, even if they are feat or proficiency gated (including things like Clinch + Knees), so at this stage I am more figuring out what I want to represent first, and then working on the how.