I would guess that worldwide most highway=path are unpaved, and most countries have more important things to worry about than putting up signs and worrying about whether or not people cycle there. The suitability of these paths will vary a lot depending on the terrain.
I’m thinking of something like
It may well be that both walking and cycling are legal there, but that’s still quite different from a shared-use path.
But I’m not sure this distinction is worth the effort to establish yet another highway tag. We already have cycleway (the second example is in Britain so it’s mapped cycleway) and even in communities that don’t want to use cycleway, tags like surface and smoothness exist that can make the difference clear. I don’t see how it can harm to add a subtag path= either.
The sort of examples where I do think it would be good to move to a different highway= tag is scrambling and mountaineering routes: