You definitely have to sort. If not they will simply weigh the box as midgrade and toss it aside to sort themselves some time in the distant future.
As for a scale, you can pick up an entry level one on Amazon or walmart for about $20. They are usually 1oz-20lb scales with an 0.5 accuracy.
Great for weighing boards.
Quick tip. Weigh the empty box first. Then add all the weights of the items you put in the box to that.
When done add 6oz to the total weight for a buffer. That’s your shipping weight since an entry scale can’t handle above 20 lbs or so.
Personally I have these two
https://a.co/d/01jel6RZ Just stay under 50lbs on it.
This one is the same price and absolutely amazing for packages. It’s low end weight spread isn’t usable though. Under 3 ounces it’s rather worthless.
https://a.co/d/003fwENcHave two of these. One for the office to weigh packages.
One in the garage to weigh scrap.