I should also add that that /ɥ/ in English words does sometimes appear in the speech of some French people, particularly older people I think. Case in point: my mom :') Tɥits, le ɥik-end, etc., whereas the more standard way to say it is with a /w/. The difference with wagon for instance I would guess is that it was borrowed a long time ago, whereas week-end is probably a more recent loan.