I use Plex in my home and there isn't a client for VR. However, I use Skybox VR and it can connect to network shares and play movies from there. So, it doesn't have a nice interface like plex, but it does a good job of playing the files. You would just have to make sure that the drive is shared on your network.
i7 8700, 16GB, RTX 2080 TI, Rift CV1 | i5 4690K, 16GB, GTX 1660 TI, Rift CV1 | Quest | Quest 2