How to implement SWD lines on Type A to C USB cable
Instead of inventing your own debug connections over Type-C connector, I would advise to align your project with Type-C Standard, "Debug Accessory Mode", see Appendix B of Type-C Specifications. But if you want to use Type-C and mark it as proprietary debug port, you can do whatever you want with connections, provided that you use GND and VBUS pins properly. Accidental connect to live USB port will do no harm other than "fail to connect/enumerate" message. The error will come and go, why be concerned?