@silverpillWith NIKE (Non-Interactive-Key-Exchange) one sided forward secrecy is the best you can get. AFAIK the fediverse model strongly favors 0-RTT messaging, so I think the FEP as designed is close to ideal, as something simple that fits the use-case.
I will be the first to admit that my knowledge in the protocol is severely lacking, but if you have cryptography related questions, please let me know.