Convert eddsa public key fro PEM to DER

[Robert Moskowitz <rgm@xxxxxxxxxxxxxxx>]

I googled how to convert a PEM public key to DER and only found examples 
for RSA keys.  Mine are ed25519.  I thought it would be a simple 
algorithm substitution:

$ openssl ed25519 -pubin -inform PEM -in $dir/private/intermediate.key.pem\
>  -outform DER -out $dir/private/intermediate.key.der

Invalid command 'ed25519'; type "help" for a list.

So since my other commands use -algorithm, I tried:

$ openssl -algorithm $algorithm -pubin -inform PEM -in 
$dir/private/intermediate.key.pem\
>  -outform DER -out $dir/private/intermediate.key.der

Invalid command '-algorithm'; type "help" for a list.

So what is the command to convert an ed25519 public key from DER to 
PEM.  The command I used to create the key was:

   openssl genpkey -aes256 -algorithm ed25519\
       -outform pem -out $dir/private/intermediate.key.pem

thanks