Do you think it could be possible to select from the dashboard the serial interface you want to use ?
In dynamic mode then.
For the moment you have to select it in advance in the editor, it would be convenient to be able to display the same choice from the dashboard and store this value in a global variable for example.
Possibly because a quick search of the forum reveals that it is not possible at runtime. There are some work arounds involving env variables and restarting node-red but no dynamic runtime possibilities at this time.