TheFork users who ate in Grimaud have said really good things about Les Santons, Chez Nous and Braise & Cow. Maybe you should give them a try!
Some of the more popular dog-friendly restaurants having a terrace in Grimaud according to TheFork users include:
Les Santons, with a 9.2 rating
Chez Nous, with a 9.7 rating
Braise & Cow, with a 8.6 rating