Yes, signed by their Nostr keys.

Definitely an option. Digital signatures ftw. Here's what I posted yesterday on X: Well done! I love the intent and execution here! To take it one step further, has River considered enabling customers to publicly vouch that the results of their validation excercise are legit? I feel like this is the last mile of this intent to really bring it home. This could be done by issuing a Verifiable Credential to customers, and then enabling a 1-click "vouch" button that compiles a message which customers can digitally sign and publish using their VC. The messages could be pushed to any verifiable data registry of your choice, but could start out as simple as just River hosting these signed messages on your website / infrastructure. This information would now be public and corroborated by your individual customers, adding that real credibility that you all are going for in terms of an open, public certification process.