I haven’t tried it (I don’t make bugs, so I don’t need a debugger 
- ya, right - but you should be able to follow the better documented trail for the S2 and S3 variants. There are a number of posts like
…and many more. There are even a few YouTube videos on the topic.
It SHOULD work like S3 and S3, but given the current state of support for the newer Espressif parts, I wouldn’t die of shock if some needed configuration file in platformio itself hasn’t added it to a table of targets to start openocd or whatever.
I don’t have a C6, so I can really only cheerlead.
Good luck.