Plume (the federated blogging app) is not handled. The error message is "None of the matched service providers could be verified. Keyoxide was not able to determine which was the correct service provider or why the verification process failed." On the other hand, Pixelfed (the federated photo sharing app) is working (but considered as "pleroma"). Example: https://keyoxide.org/hkp/FFD0B3DDAD69CB71BAE13B1DDFFF34860D361C52
Optional API documentation URL:
The idea is to handle Plume like Pixelfed, with the "[Verifying my OpenPGP key: openpgp4fpr:...]" in the profile description.