Does 5G make much of a difference here? From what I've read, in the the bands that give you reasonable range (mmWave doesn't work at these distances), 5G at the very most gives you like 20% more bandwidth than 4G LTE. That doesn't seem game-changing.
From the competition section of the site, the sweet spot for WISPs seems to be just under suburban, where there's enough density but not quite cable coverage (or the local cable monopoly isn't giving their network enough TLC)
This is my opinion as well - 5G will improve latency and also capacity (meaning carriers won't have to be as stingy with tethering plans) but not necessarily top speeds or coverage area.