Found this, which seems to get close.
https://stackoverflow.com/questions/72152837/get-public-and-private-key-from-pem-ed25519-in-c-sharp
I'm unable to create an EdDsaSecurityKey object from it.
I'm new to BouncyCastle and EdDsa in general.
I'm trying to setup JWTs with EdDsa instead of HMACSHA256, but as stated before, I'm unable to import the keys.