The Intel® SGX Commercial License table shows that a "Third party" Launch Approver can be used with a "Third-party attestation service" or the "Intel attestation service."
Does modifying the launch enclave allow use of Intel® SGX Attestation Service Utilizing Enhanced Privacy ID (EPID)?
Modifying the launch enclave has no effect on the method of attestation. You can use either Elliptic Curve Digital Signature Algorithm (ECDSA) Attestation or Intel® Enhanced Privacy ID (Intel® EPID) Attestation with any launch approver.