What hardware, software and paperwork do you need to do such a thing?
Somebody also shared this guide on building a wireless ISP in that thread: https://startyourownisp.com/
At the end of the day it's like any other business, you start it, get staff that knows how to make it happen and do it. The networking knowledge is pretty straight forward to learn. If your interested in putting fiber or other wires in the ground or on poles you may have some utility regulations that can be difficult to navigate. Especially if you need to cross rivers or use bridges.
Really this kind of a complex question to answer as the specifics matter.
You only need paperwork if you're in a paperwork heavy society and/or if you're going to use public right-of-way to pull cables.
I suspect the hardest part is regulatory, and doing customer service.