I've often considered dynamo hubs and even fabricated a tire-contact generator to recharge my smartphone and lights when touring but have found that a solar battery pack in conjunction with a AA (blinky lights) and 18650 (headlight) battery recharger fits the bill nicely for my smartphone and lighting needs and it's also useful when traveling without a bike. The battery pack also came with two USB LED 'reading' lights that are useful when camping.

Something like this:
https://www.amazon.com/Portable-1000.../dp/B013WKTI16