This is true. Except for the boat ride's link to the Translatio of St. James, the rest of the modern Spiritual Variant actually hangs its hat on the story of one (that's ONE) 18th century pilgrim, Father Martin Sarmiento, who made a circuit of the O Salnés region in 1745. His route took him through the towns of Poio, Sanxenxo, O Grove, Meaño, Cambados, A Illa de Arousa, Vilanova de Arousa, Vilagarcía de Arousa, Catoira, Valga and Pontecesures. From there, he continued to Santiago de Compostela and, later, explored the most northern areas of Galicia around A Coruña and Ferrol.
Note that Father Sarmiento did not include Armenteira or the Ruta da Pedra e da Auga in his itinerary. In fact, half the Spiritual Variant, from Combarro to Vilanova de Arousa, has nothing to do with either the Translatio or Father Sarmiento. And that's the most scenic part.
The authorities in O Salnés recently recognized a second trail, the Ruta Padre Sarmiento, that continues around the peninsula from Combarro to Vilanova de Arousa and truly replicates Sarmiento’s journey. This route, however, is not yet approved by the Church for receiving the Compostela.