Oh that Achavi thing is super neat, thank you!  And yes, sorry, I conflated LA and LA county in my memory of when it became legal but fear not, I read all that mess about how all the different cities do it haha.

From the first link you sent it seems like if I move forward using the path tag but do my best to be specific about access tags, I should be in the clear?  Seems like they're saying there is no consensus on good assumptions - so in my mind the answer is go literal: if it's not just for foot it's not a "footpath".  Especially considering the default tags for "path" include bicycle=yes and for footpath they include bicycle=not specified.

Oh, and I'll try to do surface if it's super obvious but I haven't done much diving into the different surfaces yet so it seems daunting when I'm trying to get these paths constructed