Why, consider a device, like a mobile phone, which is not connected to power grid (solar-charged instead) and uses radio to access the Internet (typically 4G). I think it would be as off-grid as it gets. Quite a bit of off-grid equipment, like weather stations, traffic cameras, etc do exactly that.

Yeah, I would guess you can go a long way with a USB battery based charger device in the middle even... Panel > Battery > Phone... which should hold more than a day's usage for the phone.. since phone batteries tend to lose a lot of life after 4-5 years.