Create a private group and send messages to it

[FliXii]

Hello,
For my thesis i am trying to send data through nostr and the goal is to create something like a project group.
Basically a private group. So far i found public channels or NIP-28 and 87, but they seemed to consume a lot of effort to implement.

Is there an implementation that is simple to use and can be seen on clients like Amethyst?

Best regards