openssl pkcs12 -in file.pfx -out file.nokey.pem -nokeys

openssl pkcs12 -in file.pfx -out file.withkey.pem

openssl rsa -in file.withkey.pem -out file.key

cat file.nokey.pem file.key > file.combo.pem

The 1st step prompts you for the password to open the PFX.

The 2nd step prompts you for that plus also to make up a passphrase for the key.

The 3rd step prompts you to enter the passphrase you just made up to store decrypted.

The 4th puts it all together into 1 file.