I didn't do the Camino Portuges in Portugal, but started in A Guarda. The Way between A Guarda and Baiona is an easy walk and is beautiful. It's about 2/3 walking on the road, but the ocean is always on your left. Because of hip issues, I didn't take the rocky trail over the ridge from Mougas but stayed on the road (good shoulder facing the traffic).
Don't miss the harbor in A Guarda. It's like a postcard with lots of restaurants and bars along the water. I had incredible seafood there. Baiona too is a pretty town with lot of food options, a well as history. There used to be a bus that ran between A Guarda and Vigo, stopping in Baiona. I'm not sure if and when it's running.
Buen Camino.