Every name
under our own
domain.

This demonstration lists denyfirst.dev and nothing else. The hosts it may touch are compiled into the binary, so the field is fixed rather than open: a page that took any domain and then refused it would be advertising something this deployment does not do. Run the tool yourself to list your own. No name is invented. The names come from a public register of certificates, from the records this domain publishes, and from the certificates its own hosts present. What is asked, who is asked, and what it cannot show is written out in full.