Thanks for the suggestion.
Got your point but here the problem is users don't want to use PowerApps in mobile. They just wanted to access application.
I think that is not possible, because we need Microsoft platform to run the application created in PowerApps.
Regarding permission and licenses, I'm not worried because it's just a one time activity and for fixed users that is not going to change frequently.
And you are saying about adding another layer around the app ! how does that works ?