Personally, I'd just take my one and only left #Pi0W, hook it up to that #PoE board [ https://www.waveshare.com/poe-eth-usb-hub-hat.htm ] and shove USB sticks for WiFi & LTE into it and if I can't hook it up to a #StromPi or use a #USB-#Powerbank instead, I'd propably get one of those rechargeable Battery HATs.
Sadly I've only found some #LiPo / #LiIon and only two ever with #LiFePO4 instead...
#LiFePO4 #liion #lipo #powerbank #USB #strompi #poe #Pi0W