A few years ago someone suggested that powerbanks sold for use with solar power systems usually had pass through capability, and he cited a Voltaic that he had bought. I do not recall if they suggested that on this board or the touring board, but I followed up on his suggestion. I wanted a bigger one than his, I wanted several days of capacity, I bought their V44. They no longer make that size, but they make larger and smaller ones.
https://voltaicsystems.com/battery-packs

The V44 that I bought was rated at 44 watt hours capacity. I assume on a good day without too many hills that I will average 2 watts out of my Sinewave when bike touring, that puts mine at 22 hours of riding to charge from empty to full. And that means for touring that I have quite a few days of capacity if I need it. I see improvements in their V50 over what I have, I would buy the V50 if I was shopping today. I got free shipping by buying on Amazon.

But there are plenty of touring people that just charge the powerbank during the day and charge up their devices in the campground in the evening. They do not use or need pass through capability, I have seen references to Anker brand for them. I however wanted to be able to use pass through capability when charging my GPS or phone.