Are there any anonymous registrars? I don’t thins so.
Don’t you think DNS is fairly decentralized already? I don’t really get the concern to be honest. The internet is decentralized. Root servers around the world, not centrally managed.
https://bitcoinmagazine.com/technical/simplifying-bitcoin-addresses-dns
“It’s true that DNS has an inverted tree structure that terminates at the root “.”. But even that root is fairly decentralized, comprising thousands of servers operated by at least 13 disparate operators. The legacy DNS may be logically centralized but in reality functions more like a decentralized federation of sorts.”
Discussion
Njalla is the closest