You're confusing the PCIe protocol and the PCIe connector. The connector is the "default" option for carrying the protocol, but any connector with enough pins can serve PCIe. For example, M.2, MiniPCIe, Thunderbolt, U.2, and many more use the PCIe protocol but a different connector. Framework just made another connector that works with the PCIe protocol. You can adapt it to full PCIe or M.2 if you want, but PCIe or M.2 cards can't just fit in without an adapter.