This ad doesn’t explicitly state it, but I expect that Épicerie de Corossol, the small store near Au Regal, will be open from 07:00 until 12:30, and from 17:00 until 19:30 on both Easter Sunday and Easter Monday. It’s a small store, but you can get some essential groceries, sandwiches made to order, and a liter of oil for your outboard.
Jojo Supermarché in Lorient will be closed on Good Friday, April 19. They will be open on Saturday the 20th, and closed on Easter Sunday and Easter Monday, the 21st and 22nd.