With v258 we considerably extended this work.There's now a well defined way to extend the factory reset logic so that other subsystems can be reset too. And we do ship one plugin for that (which is enabled by default), that requests a TPM reset from the firmware.
If your OS is properly set up for that you can now issue "systemctl start factory-reset.target". This will initiate a reboot, but a special one, where first the firmware will reset the TPM, and then the OS will reset its own state.