A little follow up here, it seems the remote directly address an end device (or several) and cannot address a bridge. And therefore it doesn’t seems possible to use the dimmer function with a bridge.
Except your bridge can pretend being a lamp…
For those understanding French, there is an article explaining that from the creator of the Zigate:
Mais alors ? comment fonctionne ces télécommandes et pourquoi ne sont-elles pas interprétées par la ZiGate ?
La première chose à remarquer est que l’action, sur le bouton de la télécommande, est envoyée à un groupe et non pas à un endpoint (device).
A quick translation:
But then ? how do these remote work and why are they not interpreted by the ZiGate?
The first thing to notice is that the signal, when pressing the button of the remote control, is sent to a group and not to an endpoint (device).