Thanks so much @RomainMaltrud!
So it seems there are two steps to this - first, we need to identify the object with code=poleactivite in your dataset, then read the corresponding value and parameter details.
This is how it could look in a workflow:
This returns both id and label at the end of the flow:
Hope this helps! I’ve also posted recently over in this thread, explaining a bit more of these JMESPath search string work.