on Aliexpress, Julet M6 pigtail pair is $2.99, while USB-TTL breakout (with female USB-C connector) is $1.40 - even for nice CP2102 with unique serial number.

If you have a portable device which needs serial connector, don't bother with weird connector and bespoke adapters which will get lost. Go for USB-C directly. As an extra bonus, USB-C is significantly more electrically rugged than raw UART input.

(this does not apply if you have some sort of multi-port serial port server, but those are pretty rare, and most likely use real RS232 voltages anyway)