You have to use a public DNS registrar, and that DNS record has to point to your public IP if you want to automate to a public CA. All of my subdomains are in my local DNS server though and I use a wilcard for them. So no one externally can go to jellyfin.mydomain.com, but they could go to www.mydomain.com to my IP, but that doesn't forward on my router either.
But also only automated scrappers are going to look for my domain too and they are going to be blocked in the same way automated scrappers for residential IPs are blocked. I could be wrong, but I don't think there are ways to bypass security with knowing the domain name tied to an IP.
Nothing special, just WaPo, NPR, NYT, etc. I just prefer aggregating all those sites instead of going to them individually when I some that kind of news.