can this run non-ephimerally?

[My1]

while ephemeral crypto is nice for PFS in communication, sometimes you want to encrypt for storage, and you dont want a pure symmetric encryption, as obviously whatever doing the backup would need the symmetric key.

and you dont really have a seperate transmitter and reciever, so the question is basically whether one cannot just use the public key to encrypt a random secret for symmetric encryption similar to RSA?