I was able to setup a PWA by editing:

https://yourdomain.com/plugins_public/onesignal/manifest.json.php

also inject to every page:

<link rel="manifest" href="https://yourdomain.com/plugins_public/onesignal/manifest.json.php?bx_name=...">

With this setup I could have multiple PWA's for site wide, for specific groups etc.