a domain is a big ask for some p2p applications. Not only does it cost money, but you have to interact with a (central) domain registry, which defeats the purpose.

There really ought to be a system (like .onion services or eepsites but without the mixnet/anonyminity) where you can just register a domain by a public key and have a signed pointer to your address on the internet as DHT. Sort of like IPNS or GNS but more common so you can just point someone to a domain like "0x1234[...]ABCD.ed25519.pubkey" and they can get a secure connection to you at whatever address you have.

Sounds like Namebase.

Sort of. The solution i'm suggesting would occupy the "decentralized" and "secure" position of zooko's triangle (https://en.wikipedia.org/wiki/Zooko%27s_triangle).

Whereas the problem that Namecoin, ENS, and others (presumably namebase as well?) are trying to solve is squaring the whole triangle with a petname system that sacrifices security for human-meaningful names. They are what's referred to as a petname system.