no all you need to do is have:
apps:
my-app:
plugs:
- serial-port
and then the snap declaration will be issued by the store team which will automatically connect your serial-port plug to the snapd:cp2102cp2109uartbrid plug when installed. I would recommend trying this out first before building a purpose built gadget as that is more maintenance than using greedy hot plugs, which were designed for this exact problem.