Does Resources.UnloadUnusedAssets call GC.Collect?

No it isn’t anymore, we’re overhauling that part of the documentation at the moment anyways (also see this thread) so I’ll correct that as we do.

Note that Scene Unloading still does also trigger GC.Collect in parallel to Resources.UnloadUnusedAssets but we’re considering dropping that, particularly for asnyc scene unloads, as it hampers smoother async loading.