If you are talking about https://github.com/nostr-protocol/nips/blob/master/02.md
Blowater, currently, does not even support it LOL.
The contact list you see in the UI is a computed view based on your DMs.
NIP2 was a bit confusing during the implementation so that I didn't even use it.
An encrypted version of NIP2 will be much more useful. Blowater can indeed support it first. But it will take longer to make it a NIP.
It's better to just have encrypted tags as a NIP.