Not to discourage usage of OSM at all, but you can absolutely download offline maps on mobile with Google Maps, they’ve just hidden it a bit. If you tap your account icon in the upper right, a menu pops up that includes offline maps, and it’ll let you select boundaries to download.
Transmission over long distances is much harder with power since you have to send it through cables that have some resistance; fiber optic cables are reflecting light that doesn’t degrade as quick.
I think this is doable, the only question is, at what cost? Losing a lot of energy is inefficient, but that’s only if you care about the efficiency more than the result (getting cleaner energy to a place that wouldn’t have it otherwise). There may be better solutions, but I appreciate the desire to get this going here.