Blender

Pretty sure Blender has a Python API. And AO research on its own probably won't yield much juice for what I described. The topic of limiting the scope of AO calculations to calculate other things is kinda not a thing. I actually used it as the subject of my Master's thesis. I was using it to calculate the exposure of scenes to the solar ecliptic throughout the year so I could calculate fading from direct sun exposure on textures. That is why I shared a step-by-step instead of a link. The principle for what you want to do is the same though. Measuring the exposure of geometry against some other geometry.

From what I just read, you want to use the Scene.ray_cast() function. Usage should be straightforward.

For point in buildingPointCloud:
    TotalHit=0
    For destination in parkPointCloud:
        hit, _, _, _, _, _ = Scene.ray_cast(depsgraph, point, destination-point, length(point-destination))
        TotalHit += hit
    Visibility = TotalHit/len(parkPointCloud)
    FunctionToStoreVisibilityOnPointOrInList(Visibility)

That should be enough to get you started. I am 99% unfamiliar with the Blender Python API, but this should get you there if you are even remotely experienced with it. There are obviously optimizations that can be done as this is very brute force, I was just trying to illustrate the basic loop.