there is a new smartphone feature. seen in an samsung tv-add. i think this is great idea for all mobile devices.
hold your full battery loaded phone next to another phone with nearly empty charged accu - and load the other
phone accu with yours.
simply spend/share some volts or ampere, if you have enough accu 
Seems very gadget for me but why not in a later version of the Librem 5 as I would find it very surprising to get that at this point in time.