The Breton galette is a sandwich the way a wrap is a sandwich, which is to say at some angle to the form rather than directly inside it. A buckwheat batter is poured thin on a cast-iron crepière, cooked on one side until it sets and lightens, flipped briefly, then folded around a filling and served on a flat plate. The classic is the Galette Complète — ham, gruyère, and a fried egg in the middle, four corners folded toward the centre, the yolk barely set under the heat of the bread. Eaten with a knife and fork, washed down with cider.
The filling vocabulary is regional. In Finistère the Galette Andouille adds the smoked andouille de Guémené. In the Côtes-d'Armor it's a Galette Saucisse — a grilled pork sausage wrapped in galette dough, the closest the French ever got to a hot-dog vernacular. In the Pays Nantais the lighter, sweeter wheat-flour crêpe — Crêpe Beurre-Sucre, Crêpe Jambon-Fromage, Crêpe Nutella-Banane — extends the form toward both the savoury lunch and the post-cinema dessert, and the line between them is roughly where you decide to add chocolate or another egg.
The galette and the crêpe disagree about what bread should be. The galette is rustic, slightly bitter, naturally gluten-free, and tied to a specific Breton agricultural history. The crêpe is sweet, light, butter-rich, and a national dish. Both end up being sandwiches when you fold them around something — and the fact that two completely different breads from the same northwestern corner of France end up doing the same job is a fair summary of how unwilling French food culture is to draw narrow lines around its own categories.