I have found a few workarounds myself.
For the VR Camera moving inside the pawn: temporary fix is to, every frame, reset the HMD’s position via the “Reset Orientation and Position” node.
As for the inputs not firing, in the HMD in Steam Link i had to set up my custom control scheme, where any thumbstick input is only received if using “Oculus Touch ([Controller]) Thumbstick [Direction]” input key in project settings AND in the HMD itself the input is configured to fire on “Touch” as “DPAD” (Each thumbstick direction gets configured as a separate DPAD input “block” in Steam Link, so:
L Thumbstick -> Use As DPAD (Touch, North: VRMoveForward, East: None, South: None...);
-> Use As DPAD (Touch, North: None, East: VRMoveRight, South: None...);
and so on). However this only allows the thumbstick to send input values of either 0.0 or 1.0, so basically no axis input, e.g. no slow walking.