I do know that such a thing is possible, due to RoboRecall displaying a scoreboard on the Spectator Screen while someone else’s playing.
Leaving the UI for a Spectator Screen while the player itself has a totally clean view through his HMD would be extremelly beneficial to VR Experiences.
Think of this. While someone’s playing the game on the HMD, someone else with the Spectator Screen on a Table or Desktop Display, could very well change in Real-Time an asset’s material or even the loaded level through level streaming.
I second this. I’ve been looking/hoping for this since the spectator screen was released. The ability to interact with someone next to you that is in VR instead of just watching them have all the fun would really round off the spectator screen. There are many threads with ideas and hacky workarounds to add or at least display UI on the spectator screen, so there are definitely people in need, but it seems the only real solutions for this are C++. I’m sure it’s lazy on my part, but it seems like the native ability to add widget to spectator screen via blueprints would be a HUGE help.
Good news! I’ve created a plugin to do just that. It creates an extra window in which you can have all the UMG you want and you can interact with it as normal. We found little overhead from the window in our projects. You can find it here: VR Spectator Control Window in Code Plugins - UE Marketplace
Here’s an example video: https://youtu.be/ceV0F-8ybvg