Honestly, stop overthinking it and just install Keepa right now! I've been using it for over five years and it has literally saved me thousands on tec...
Make sure your bank has PPS like the Baseus Adaman 2 30W 10000mAh Power Bank for fast speeds. I'd suggest the Ringke Onyx Case too so you dont drop it...
Saving this whole thread. So much good info here you guys are awesome.