Position: Experimental 6DoF tracking support with external SLAM/VIO systems is upstreamed but still being worked on. Tested with RealSense D455 and Samsung Odyssey+, Reverb G2, Oculus Rift S.
Additional Notes: HMD only, no controllers. Tested: HP Reverb, HP Reverb G2, Samsung Odyssey, Lenovo Explorer, others: maybe.