>Also could you theoretically utilize headphones built-in DAC if they are wired and would it be better than integrated dac in the motherboard?

You could, but it depends. There are some gamer USB headsets that most likely have a DAC inside them but I doubt it would be a good one. Apart from that your only chance is probably wireless headphones that can also be used wired, and those are also pretty rare (and most likely won't use their DAC when wired).

Really given that a $10 apple dongle is very good for the size/price there's little reason to depend on any headphone -internal DAC unless it's wireless.