I planned to implement an own social network on this idea, and nostr is not really made for it, but here you go :):

You can write an e2e encrypted question to your friends, they can answer it or push it to their trusted contacts with e2e encryption. Only involved people can read the answers. The question has an own public/private-key pair. Question-creator and answer-creator can optionally stay anonymous.

The idea came during Covid :].