Well... Look at
this bank. Looks like it could take 4A (see 4th picture).
Hmmm... the forumslader. I've removed it. Issue with the steerer cap cables. Haven't long toured since and no out-of-the-way plans. So it lays somewhere in a drawer.
I will try to use a smartwatch and see how it goes. Looks like it does its thing on 100mAh per day. At least one order of magnitude better than phones or computer heads. Game changer wrt power management.
Still months away. Several options to consider