For those of us stuck on normal android, is there a way to achieve that? I know it used to work with some firewall apps but nowdays they all require root access.
Netguard No Root Firewall still works for me: https://github.com/M66B/NetGuard
It looks like you can't revoke the internet permission, but you can use the firewall via ADB. Settings are lost on reboot, but you can use an automation with Tasker or similar to set them on boot:
https://www.reddit.com/r/tasker/comments/1mxjnvs/how_to_bloc...
Not the same thing, but you can install an app like Blokada Libre to block ads and trackers in all apps.
Go to settings > App > $SCUMMY_APP > Mobile Data & WiFi. Uncheck all.
Rethink DNS can block internet access of an app (besides doing DNS-based blocking, etc.): https://rethinkdns.com
It uses the VPN functionality, but you can stack a Wireguard VPN on top of it.