Do packets routed to another interface using `pf`'s `route-to` option on macOS actually pass the given interface?
I've read that pf's firewall rules only applies to packets that (physically) pass the given interface.


I remember answering to your similar question on unix.stackexchange.com


  Thus, rules for a gateway's external interface will not apply to packets entering on the local interface and destined for the external interface, since the TCP/IP stack handles such packets internally.


Pf's rules do apply to traffic over loopback too unless you're specifically exclude it with smth like set skip on lo0.

You also better keep in mind that Pf's version shipped with MacOS is severely outdated and some documented features of Pf don't work at all or work incorrectly. route-to is somewhat "hacky" feature and I won't be any surprised if it'd fail in similar ways.