Even an external firewall can't easily block everything. Just send telemetry over port 443 to an AWS server and most can't block it. You can't trust a device that need an outgoing firewall.
Re:Bypassing Firewalls in macOS Big Sur
by justinclift on Saturday November 14, 2020 @11:53PM
(#25098362)
"use a firewall" -> "use an external firewall". :)
If you want to block something use a firewall.