Hi Innav and Welcome !
I walked from Porto in 2021 it is a lovely Camino! ( i love the sea)
As suggested above if you want a Compostela you need to walk the last hundred Km and get two stamps a day.
Walking to the Cathedral and into the Obradoiro Plaza was amazing and emotional; i walked in with a Puerta Rican lady called Gina at nearly 7 pm on October the 10th and it was full of pilgrims cheering and waving flags (one Spanish flag was about 3 metres wide).
I think you can start in Vigo or Tui!
The second half of my Camino was the best bit for variety mountain,forest and sea side walking (especially the Espiritual Variant which starts just north of Pontevedra and very easy to find (large billboard by a small bridge) I will defo do this part again one day it is beautiful!)
Combarro and Armentiera and Villanova de Arousa were places to stay.
I stayed in the Monastery in Armentiera the Hospederia has private rooms but not sure if available end of March
These were my stages (sorry my spreadsheet has lost the distances but none were more than 20 to 25km i am pretty sure.)
|VILANOVA DE AROUSA (Boat ride to Pontecesures)|
Whatever route you take have a blast.
You will meet great people and have fun.