I've been doing something vaguely similar, largely out of laziness, for the past few years. My ISP's router (largely) retains its default settings, then my main

I've been doing something vaguely similar, largely out of laziness, for the past few years. My ISP's router (largely) retains its default settings, then my main router/firewall[1] sits behind that in a double-NAT configuration (treating the ISP router as being on the WAN side). Works well enough in practice - it's never caused me any issues in the ten or so years I've been doing it (port forwarding becomes a two-step process, but I _very_ rarely need to do that, so it's a non-issue for me). [1] Typically pfSense, though it's just a generic Eero setup for now while I reconfigure some stuff33333333