ahhh very cool! Thanks so much for sharing this @AntonMoss !!!
i have seen quite a lot of flavours of reverse feet in maya. for now the default reverse foot is fairly classic and we kepts the foot roll on purpose seperate on the abstract controls and leave all reverse pivots exposed. It is a fairly save middle ground between giving something for automation, but also expose maximum control.
Just sharing a moment of what i have seen and also done in production, and the realities of it. Cause i got burned with that too

Coupling main controls to automated behavior always looks amazing and is super fun to build for a rigger, unfortunately you can get you proper pushback from some animators. And then you spend a lot of time building that automation and it looks very awesome and you are soooo happy as a rigger, but the animators instantly turn it off cause they can not set the exact angle they want to set when then want to set it.
This is of course just what i have seen so far and absolutely nothing speaks against building a setup like this. Thats the cool part about rigging that there are so many different solutions and so many different types of animators

. I can only recommend to really ask your animators if they like automated setups before adding them, to save yourself and the animators a moment of unhappiness