I was going to propose an encrypted textnote kind with Consent Request/Response kinds for medical information.
It would fit right into your idea.
Discussion
Like this.
It could be reused into many applications.
Notice how the secret owner might not be the author.
Secret-Encrypted Kind
{
pubkey: // Author's key
kind: 900
contents: .. // information encrypted with a shareable secret
...
}
Consent Request Kind
{
pubkey: // Requester's key
kind: 901
tags: [ e: 900-event, p: 900-event-author ]
...
}
Consent Approval Kind
{
pubkey: // Shareable-secret owner
kind: 902
contents: .. // shareable secret encrypted with consent requester's public key
tags: [ e: 900-event, p: 900-event-author, e: 901-event, p: 901-event-author ]
...
}