Nope, red error. Domain name is invalid! It's not a big deal, to be honest as most devices are accessed by IP anyway, the only DNS name that matters is the one of the PIhole itself so it shows to the router as one name, not multiple, which is the intended goal, to make routing in and out easier. I say that after I said:
I'm sure I will find a nice webui interface for firewalling stuff.
Thank you for your help @deHakkelaar. As with everything like this, there's always more to be done, but it's working for now, fulfilling two of the three purposes, showing as one interface to the router for easier management on that end, and blocking adverts this end. Next will be getting ports forwarded through, a VPN set up, as well as some other items I can't quite remember now.