I have a cheap binocular microscope at home, and solder most everything underneath it. A USB microscope is much lower resolution, and the image lags. They're pretty terrible.
At work I get to use a very very expensive Olympus binocular microscope. It is extraordinarily good, but at about 60k it costs more than a car.
My digital microscope has no lag and brilliant resolution. You can easily solder under it just looking at the screen. Just don't get the super cheap ones but one for maybe 150€ or so.
Yeah you can get an old Bauch&Lomb for under $200. Probably need an LED illuminator ring for $10 too.
They have great field of view (cm) at decent/variable magnification (20-100x) and response time is instant, whereas your phone/USB are going to have just enough delay to be annoying.
At work I get to use a very very expensive Olympus binocular microscope. It is extraordinarily good, but at about 60k it costs more than a car.