Is it possible to restrict assets in multi region/site specific similarly to how you can restrict entries? Is it possible to assign regions to assets similarly to the way that we restrict entries to a region for multi-region/sites?

Ideally I could specify a path for each region/site as well.
Currently Asset Volumes in Craft 3 are defined on a global basis.  If you would like to see differently, you can create a feature request and be sure to include your use-case. 

Asset fields have advanced settings where you can relate Assets from a specific site or not in the Control Panel under Assets->Fields->(your Asset field)->Advanced