I don't think it's going to be military killing a Americans. As of now it more looks like federal government.

Nevertheless, sure, in the rural areas, but less so in the cities, reflections and bending of the waves make it much harder, and a single repeater with solar panel and battery could plausibly be made under $50.

A military won't be killing all Americans, just the ones it can label as "terrorists" to the people who elected them.

They are being made. I have a four node network already in my suburb. There is a software project that is written in Python that essentially turns lorawan nodes into BBSs similar to briar.