For Pixel sale, you can use
https://astronomy.tools/calculators/ccd_suitability give that a try and see how you go.
USB 3 is not a bad thing, it means that for bright objects (solar system) you can increase your frame rate, however you can also use them as USB 2 devices by using a cable without the extra pins or attaching them to an older PC/Mac so it give you a bit of extra flexibility.