Firewall in Android

Hi! Two phones:
1) Google Android 10
2) GrapheneOS
Both have VPN via Wireguard.

Is Firewall needed or useful? If yes:
1) NoRoot firewalls wont do, due to existing VPN. Correct?

2) Is AFWall+ on F-Droid trusty? Requires root. Would it harm the security on the phones? Pros an cons?
https://github.com/ukanth/afwall/wiki

3) GrapheneOS has its own firewall but could not find the ui controls for it. Where is it? Would AFWall+ harm it?

Thanks for feedback

Well i don't think it possible to use any sort of firewall without utilizing the VPN slot as a means to gain access to the network traffic.
i would not recommend you to gain root access.
Root access will ass far as i understand pose a great security risk to your OS.
Read GraphenOS docs for more information about risks with root access.

I have no idea what you seek to block with a firewall, perhaps a dns block-list utilizing DNS over tls will work?

Thanks for the replies. Dropped the idea to use any Firewall app

Also ….. don’t root.