I have set up local DNS entries (with Pi-Hole) to point to my srrver, but I don't know if it possible to get certs for that, since it is not a real domain.
So long as your certs are for your fully qualified domain there's no problem. I do this, as do many people
mydoman.com is fully qualified, but on my own network I override the DNS to the local address. Not a problem at all
DNS is tied to the hostname, not the IP.
Kimi got out of the sport just in time I guess...