For other great french mustard, not from Dijon you have :

"Moutarde de Meaux" (or "Moutarde à l'ancienne"), a mustard done the old way. One of the best producer is Pommery:

https://www.moutarde-de-meaux.com/pommery

"Moutarde de Normandie", the same than the above but with cider vinegar:

https://toustain-barville.com/3-moutardes

"Moutarde violette de Brive", yep! it's purple:

https://www.denoix.com/moutarde-violette

"Moutarde à la Violette", this one is not purple, but do include extract of violet flower:

https://www.lamaisondelaviolette.com/fr/epicerie-salee/101-m...