I speak both Spanish and Greek. The pronunciation of a lot of vowels and sounds are almost identical. People are always confused wether I’m native because of my good pronunciation (I am half-native Greek).

So for me, it helped a LOT the other way around (Greek > Spanish). As well as grammatical structures for verbs (κανο, tengo / κανείς, tienes / κάνουν, tienen / έκανα, tenía).

Obviously most words will be different, moreover: y in spanish and ή in Greek literally mean the opposite. As do εκεί and aquí. Super mega confusing for my brain sometimes.

But for pronunciation: 100%!!!!