Need access to Amplify automatic Route56 domain TLS .pem and key

I've got an API configured to connect using MTLS using this documentation: https://aws.amazon.com/blogs/compute/introducing-mutual-tls-authentication-for-amazon-api-gateway/

As a human, I can make an API call using my client cert and private key.

As an Amplify site, my client cert needs to be in the API's configured truststore and I need to use my private key to make the API call.

How do I get access to the Amplify/Route53 auto configured certs PEM file and its key? It does not show up in ACM for me and it doesnt appear to be availble through the amplify console. Alternatively, can this be leveraged through the SDK somehow?

Thanks!