Just because the title doesn't make it clear, .onion is reserved for Tor usage, as is the case today; it's not been reserved for something else. There even is a

Just because the title doesn't make it clear, .onion is reserved for Tor usage, as is the case today; it's not been reserved for something else. There even is an RFC for that (https://datatracker.ietf.org/doc/draft-ietf-dnsop-onion-tld/?include_text=1 https://datatracker.ietf.org/doc/draft-ietf-dnsop-onion-tld/...)