Inspired by a post on the fediverse: https://sonomu.club/@luka/108747429639661280
The DOIP library (and by extent, Keyoxide) only verifies proofs if it finds the OpenPGP fingerprint in it. Since keys.openpgp.org allows searching keys by both fingerprint and Key ID, it may be an idea to also allow proof verification via Key ID.
From what I know, both fingerprints and Key IDs are unique to each OpenPGP key pair. I see little reason to not support this.