This linux driver claims to provide USB-SPI support: https://github.com/gschorcht/spi-ch341-usb
Notes here on using that driver: https://www.linuxquestions.org/questions/linux-hardware-18/ch341-usb-to-spi-adaptor-driver-doesn%27t-work-4175622736/
Or if **absolutely** necessary could bitbang: https://www.cnx-software.com/2018/02/16/wch-ch341-usb-to-serial-chip-gets-linux-driver-to-control-gpios-over-usb/
* Port meshtastic to build (under platformio) for a poxix target. spec: no screen, no gpios, sim network interface, posix threads, posix semaphores & queues, IO to the console only