An EC private key is nothing more than a 256-bit integer. You can use openssl to extract the private key (as a 256-bit integer) from the PEM file.
Try saving the PEM file that you posted on your system as private.pem. Then, use the following openssl command to extract the private key from the PEM file:
openssl ec -noout -text -inform PEM -in private.pem
This should produce:
read EC key
Private-Key: (256 bit)
ASN1 OID: prime256v1
NIST CURVE: P-256
As you can see, the private key is displayed as a 256-bit integer in hexadecimal format. With the private key now in its raw format, it should be possible to consume in any environment.