There are sections of the Camino where sandshoes could be appropriate, however, when you are walking so many km per day it is more about the support hiking shoes offer your feet and legs. Sandshoes while comfortable on most surfaces have soles that are not created for varying terrain and in wet conditions and rocky surfaces especially they could be quite slippery and hazardous.
It is nice to have a pair with you to wear socially and if it is a flat, dry day you could wear them but please consult your Camino guide before heading out.
The most practical and recommended footwear for Camino de Santiago is lightweight hiking boots or shoes. For everyday protection, it is best if they are also waterproof. Ankle support is not important if you have no physical issues as the conditions on the French and Portuguese Camino are relatively easy.