Several methods for making loading screen, would like some suggestions and idea-sharings

Does this help you out? Sounds like a predicament, but I just saw this a minute ago and it came to mind. Apologies if you’ve already seen or considered it:

“Unreal Engine 4 (UE4) offers support for displaying videos or images while a level loads when using Oculus, Gear VR, SteamVR, and PSVR Head Mounted Displays (HMDs). The loading movie or image will run on the rendering thread and can also help to mask frame rate issues while your content is loading. In the following document, we will take a look at how you can set these VR Splash Screens in your UE4 projects.”