Yes but it works with relay permissions, I'm not a huge fan of that, I'd rather Let cryptography and gift wraps do its job even if it's a little harder.
I think lockbox is already the solution https://lockbox.fiatjaf.com/, and if you say community there are 5 solutions for 4 people :lumisimple:
Discussion
something like https://github.com/AbdelStark/nostringer-rs is, so if I tag those people in a form/rooms, I know that the generated npub belongs to them, yes it is definitely more complicated, and then the media is public
This is doable, and we can solve the media being public part via blossom. I'll check out nostringer, thanks!