Yes,
@ivar's luggage storage is still in operation.
Send your luggage to me in Santiago de Compostela
casaivar.com
If you are starting in Porto you have other options to send a bag from there.
Tuitrans offers transport directly from Porto to Santiago.
Tuitrans transports luggage quickly and safely, stage by stage and directly to Santiago de Compostela
tuitrans.com
And I used a service called Luggage Driver to send a bag from Lisbon (they also pick up in Porto)
Transfere de bagagens, passageiros e bicicletas em Portugal e Galiza | Luggage, passengers and bikes transfers in Portugal and Galicia.
luggagedriver.com