I pronounce ‘on’ like ‘awn’ because I’m from the MidLantic region where this is common. From Maryland through the greater Philadelphia area, into that Murder-Durder mix of central PA accents and out into some part of Jersey until you get north far enough to be in Joysey you’ll hear it as ‘awn’. Then you get up to Boston and the people pronounce ‘awn’ as if it’s ‘on’. And when people say “Go ask Don about that” I have to say “Who’s Don”, resulting in some confusion until I figure out they mean “Ask Dawn about that”, not “Don”. But that’s hardly the worst way they mangle the language.