Gaelic at least is a distinct language. Ukrainian and Russian use the same alphabet and similar etymologies and grammars. It’s like an older form of Russian, I think, like English with all the “thee”s and “thou”s still in it. Not claiming to be an expert.
I was also thinking about Catalan vs Spanish.
I know if you go to Barcelona, if you try to speak in Spanish to them, and they know you come from Spain, they will not respond to you. But if I speak Spanish with my heavy American accent, they know I’m a tourist and have no problems speaking in Spanish to me.