overlay app with unity?

Hi,
is it possible to create an vr overlay app with unity? I want to show something in an existing (non unity) vr game as overlay like an App with an invisible background.

thx

I don't think so.
Certainly not on standalone VR. Maybe on PCVR but that's outside of my knowledge

Hi, i only mean PCVR.
OpenXR provides an Overlay Featire called XR_EXTX_overlay and may be it's possible to define this feature in Unity. I have found two links about it but i don't know how to implement and than how to use.

https://registry.khronos.org/OpenXR/specs/1.0/html/xrspec.html#XR_EXTX_overlay
https://docs.unity3d.com/Packages/com.unity.xr.openxr@1.6/manual/features.html

this might work

https://www.youtube.com/watch?v=RqgsGaMPZTw

It's possible using SteamVR, but it's not supported well, and you'll need a beefy PC.
https://www.youtube.com/watch?v=vArWTlRieGI