As for Oakland county I think Trump would lose it 56/42 against Biden and 55/43 against Warren.
Oakland is a weird one. It is a standard typical suburban county of the type where one would expect Romney to do very well in but expect a hard swing in the other direction. Yet, Romney was born there and the county only budged by 0.1% in 2016. The county trended R heavily in the blue collar parts and D in the white collar parts. Even so, the midterms showed it vote 8 points to the left of the state, similar to what it did in 2016. I honestly don't think Trump will do better there, as black people from Detroit frequently move to places like Southfield and make it a little bluer every year, but I think the margin will be closer than people would typically expect for a county of its type.