USB Type C to DB-9 Adapter Cable - 1.5m long : ID 5446 : $17.50 : Adafruit Industries, Unique & fun DIY electronics and kits
Amazon.com: Cable Matters USB C to Serial Adapter Cable (USB-C to Serial, USB C to DB9, USB C to RS232) 3 ft - Thunderbolt 4 / USB4 / Thunderbolt 3 Port Compatible
USB-C to Serial Adapters - Brainboxes | Mouser
USB C to RS232 DB9 Serial Port Cable with FTDI Chipset
USB Type-C Serial Connector Cables - Connective Peripherals | Mouser
USB-C 2.0 to Serial RS-232 Adapter w/ LED Indicators
US-735 USB-C to 1 Port RS232 Industrial USB to Serial Adaptor - Brainboxes