This app was mentioned in 3 comments, with an average of 1.33 upvotes
At that price i'd jump on one of those devices, looks pretty cool.
This app is what i've used with an easycap.
I can hook my goggle's output to the easycap and using this app and a google cardboard i can let someone spectate pretty well. It doesn't work with all phones but it worked with my LGG4.
I've also used the easycap to record flights with that app and to fly my eachine E010. With how slow a nearly stock E010 is, the latency wasn't too huge an issue.
https://play.google.com/store/apps/details?id=com.vertile.fpv3d
Could be side loaded or similar.
Give this a try https://play.google.com/store/apps/details?id=com.vertile.fpv3d