A day late to the sandwich party, but my wife and father-in-law pronounce it "sang-wich". After years of mocking them, this thread prompted me to Google it, and it turns out that sangwich is common among native Italian (and Spanish speakers). And their kids that grew up around it, in my wife's case.
https://www.grillsdetaronja.com/en/s...h-vs-sangwich/