Generate .p12 from .pem

openssl pkcs12 -export -out keyStore.p12 -inkey myPrivateKey.pem -in certs.pem
openssl pkcs12 -export -out keyStore.p12 -inkey myPrivateKey[[.pem] -in certs[[.pem]
Enter pass phrase for myPrivateKey[[.pem]:
Enter Export Password:
Verifying - Enter Export Password:

p12

PEM, Certificate extensions, ssh-keygen -m PEM, RFC 1421, OpenSSH PEM (RFC 4716)