I have been reading a bit about BIP351 Private Payments. BIP351 uses nulldata outputs (
OP_RETURN) to create shared secrets on the blockchain. Could these notification outputs be monitored client-side using compact block filters?
Compact block filters do not index nulldata outputs. Therefore, a different mechanism would need to be used to retrieve notification outputs. Since BIP351 notification outputs have a distinct label, they could e.g. be provided as a set of Merkle branches for download, or via a new network service. All participants in BIP351 would need to retrieve the complete set, since discovery of ownership requires use of a private key and can only be performed client-side.