Valve has done a pretty good job at standardizing VR tech with OpenVR/SteamVR. All of the headsets except the oculus seem to have really good hardware compatibility. The vive controllers can be used with the pimax hmd, etc.
Facebook seems to be trying really hard to create a lockin with the oculus, if you buy games on the oculus store, you are now forever locked in to only buying oculus hardware from now on.