TLS certs without having to buy a domain? Create a GNS domain, set a LEHO record with the necessary Host name, and make your cert based on that? Obviously you'll need a CA that's willing to issue certs for GNS LEHO names, but that way you can use the current TLS CA system to a domain without having to actually spend money on one. Alternatively, have the CA issue wildcard certs for zTLDs and then you can manage your own zTLD without issue.