The minipgp6-sop ("msop") CLI tool can now be seen interoperating with other v6 #OpenPGP implementations, including using #PQC hybrid keys from the new #RFC9980: https://sequoia-pgp.gitlab.io/openpgp-interoperability-test-suite/asymmetric_encryption.html#Asymmetric_Encryption In particular, the rPGP-based "rsop" CLI tool already features PQC support in its latest stable version. Other #SOP implementations don't include PQC support in their default builds yet, but selecting any of the "+pqc" implementations (at the top of the test suite page) shows a lot more interop.