You can do so with a private relay and only invite specific users. But you have to publish your note specifically to that relay only. I dont know that there is any utility to optimize this though.
Discussion
Good idea. Though, as you might said between the lines, it has shortcommings. Not optmized.
If I think of my close friends and relatives, there are 2 groups of users:
- Posting for their friends and family only.
- Posting for social media marketing.
I think for group one, such a private social media, where they can share only with their friends, and really only their friends get to see, it has a privacy benefit. Also you might post more to your friends, if you know only they can see it.
Your answer is lockbox. It's a relay type where only those who you follow can see the notes you save to that relay.