Currently the pose set with Layer:setPose is always in world space. If you want to make a head-locked layer (for a debug HUD or a loading icon), you have to reposition it every frame. This is flawed, because the tracking won't be as accurate, and it won't update if lovr is failing to submit frames. So it would be nice to be able to say Layer:setOrigin('head') or something, to indicate that the layer's pose should be relative to the head. Internally this would use the LOCAL reference space. This could probably support other Devices too (primary use case would be parenting Layers to your hands as well), as long as they have an XrSpace.