Alternative to -rand option for genpkey

[Raj via openssl-users <openssl-users@xxxxxxxxxxx>]

When generating private keys with `ecparam` or `genrsa` in OpenSSL, it is possible to use the parameter `-rand file.dat` where file.dat is used as additional seed for the RNG, as far as I understand. This parameter is not available for genpkey. 

I would like to generate private Ed448 and Ed25519 keys with an additional random source provided as file. Is there a way to do that? I'm using version 3.1.0 btw.

Thanks in advance.

Raj