To me, the clips of the Ocracoke dialect sounded like a mix of US Southern and Newfoundland or some other Atlantic Canadian accent

I wondered about the Maritimes! I'm not familiar enough with the accent to connect it by ear—I hear it mostly in folksongs, not speech—but it seemed to make sense that they would be similar. Thank you for the valuable Canadian data point!

[edit] It's partly the vowels and partly the way all these dialects hang on to their R's.