Long time ago I used these BSD-based appliances such as opnsense, beleiving I'll have it easier with their web interfaces than with editing config files in vi.

In the long run, after investing some time into learning actual BSDs I find editing a few config files much more convenient than clicking around in web interfaces.

OpenBSD is great for a router.

https://www.openbsd.org/faq/pf/example1.html