what’s a language and what’s a dialect depends on the self identification of speakers. Catalan is similarly mutually intelligible as Portuguese is with Spanish and Occitan or Lang d’òc is similarly mutually intelligible with Catalá

at some point in the last couple of hundred years all the romance languages were to varying degrees “unified” under national projects as “Spanish” “French” “Italian” etc where before there had existed a multitude of local dialects existing on a spectrum of divergence from their origins in Latin and with varying introductions from many other cultures.

in northern Europe, German and Dutch are mutually intelligible as are Danish and Swedish