For the quickest charging on the go
1. 2.1a power bank like this one
https://www.amazon.com/Portable-2680.../dp/B082D1THV1
or
2. cig lighter+110v inverter+"fast" wall charger.
This combination will charge just as fast as you do at home with the OEM charger.
A solar power bank is WAY too slow for emergencies.