so have 3rd party db, primary file group has 10 drives, is there a way to find what database objects are on those logical drives?
All objects in the primary file group are somewhere on those drives. It might be possible to find out which specific objects are on which specific drives, but that's rather pointless and it could change later. SQL can write any object to any file in the group as it sees fit, barring other restrictions (such as partitioning, etc.).