Secure transports are built out of asymmetric key agreement and symmetric bulk encryption, glued together with symmetric hashes. The symmetric cryptography isn't meaningfully threatened by any QC we're yet aware of. Hybrid PQC/classical schemes do two key agreements (an ECC kex and a LWE kem), and then plug both results into HKDF (conceptually: a symmetric hash) to derive a shared secret.

In that scheme, you have to compromise both the PQC and ECC key agreements, independently.