NIP-87 has not been merged yet, but you can check it out here: https://github.com/nostr-protocol/nips/pull/875

imo, which NIP to adopt depends on what the client wants to achieve. My goal is to replace Telegram for large group chats, meaning supporting tens of thousands or even hundreds of thousands of members. Currently, NIP-29 seems to be the only one capable of achieving this. NIP-87, based on a shared key scheme, can protect privacy, but I think it limits group size to around a thousand members. Correct me if there are any misunderstandings nostr:npub1jlrs53pkdfjnts29kveljul2sm0actt6n8dxrrzqcersttvcuv3qdjynqn