for sure, we're thinking of doing something along those lines for our hosted product-- auto-trigger reviews upon opening PR, link to them from gh, etc. feel free to shoot me a message (ketan at dev dot fast) if you're interested in that!
If you make it hosted only, my guess is you will lose out on a number of users who cannot convince their corporate overlords to authorize yet another GitHub app. Charge the user and use their local gh access to make it work!