Hello edstoica,
I have provided an example blueprint that uses an Arrow component to point at the HMD in game. Could you give this a try and let me know if this works for you? The pin for “Device Position” provides the position within its own tracking space. I added this to the camera position for the player. This allows me to get an accurate position of the players head in game. I hope that this information helps.
Example:
Make it a great day