The regime you want is 5A, and it is not the Golden Visa
Two different things get confused constantly. The Golden Visa buys residency through property. The non-dom regime (article 5A) buys tax certainty: €100,000 a year flat on all foreign-sourced income regardless of size, €20,000 per additional family member, fixed for fifteen years. You qualify by not having been a Greek tax resident for seven of the previous eight years, and by investing at least €500,000 in Greek assets within three years. Most people who move here for the tax do not need a Golden Visa at all.