Prior countless clarifications on this question (feel free to google them) regarding tabletop rules have clearly stated that wearing a shield is okay, since it does not count as a weapon, so the condition of "no other weapon" is satisfied. So yes, equipping 1H+Shield fully benefits from the Dueling fighting style.
However: Whether BG3 currently has this properly implemented is a different matter altogether. I'd recommend to test it (check char sheet + combat log), and if it doesn't work as expected, best to report it as a bug.
