The server was knowledgeable and they accommodate in that they have a gluten free pizza crust that is prepared in a separate part of the kitchen but because their gluten pizza is prepared in the same kitchen (separate area) they could not guarantee no gluten particulates in the air. In the end, we opted not to eat there.
Overall, if you have a child with celiac in particular, I would warn that there are virtually no celiac safe options on Galiano. Be prepared to cook at your campsite or accommodation.