Thanks, I managed to make it load in fullscreen just by adjusting the manifest.json and the meta tags on the html correctly and setting on manifest:
“display”: “fullscreen”,
“start_url”: “/?fullscreen=true”,
(despite there are articles that say “fullscreen” doesn’t work).
It starts automatically in fullscreen ONLY after you have added the app in your homescreen and you start it by touching the icon. Before that step, it includes the top bar.
It didn’t require HTTPS or service workers, but I’ve read that when the app is offline the fetch event by the worker will be required by Chrome mid-2021.
Also according to Google HTTPS is required to get an install prompt, therefore it is good to have it during development too: