I don't know any specifics about providers or plans or anything, but you could get low-ish latency coverage from filling a pretty low orbit with satellites such that anywhere along that orbital path you'll have coverage at all times. Maybe <100ms, MAYBE. Might be why that provider wants 1500/month. Lotta launches, lotta satellites, lotta upkeep and whatnot.
As for size/power, you've been spoiled by mega-corporations throwing nonsense numbers into R&D on size and weight/power. Plus, you probably don't want a LiPO in a portable survival radio that's going to get beaten up and exposed to ridiculous temperatures, so you're stuck with larger and weaker batteries.
There aren't many resources, in the grand scheme of things, turned towards objects and systems that would make us independent of the infinite demon machine that most world societies seem to be eager to finish becoming.
Anyway, I'll put my soapbox up. Good luck!