O is too short. We would pronounce it close to “phone - due - lack”, but the N just nasalises the vowel - you don’t move your tongue at all when sounding it - and the “dy” sound in “due” (assuming that you come from an area that pronounces it as “dyoo”, not “doo”) becomes more sibilant.
Then you would be pronouncing it the way North American Francophones would pronounce it, and, if you master the N that nasalises the vowel, you’ll have mastered one of a pair of consonants that Anglos usually get wrong (the other being soft G or J).
Fond du Lac isn’t bad, but we up here who speak French tend to wince when we hear names like Gagne (Gagné) being pronounced “gag-nee” rather than “gah-nyeh”. Bound to happen in areas that are English-speaking, of course, but… ewww.
However, Wisconsin is great - they have curling.