I have both 10k & 20k mAh power banks with the same four lights as yours (Anker) so I totally get what you are saying, but as big as those numbers seem, a power bank’s energy is finite.  While I tested it with my flip-phone,the solar panel’s primary job will be to keep the power banks charged.  
Besides camping and hiking, one thing I am gearing for is a major EQ which disrupts the power grid and maybe disrupts our way of life.  Hikermor has already been kicked out of his house by a mudslide — unexpected stuff happens.    Portable solar is a good way to mitigate — at least with the smaller things.  It won’t run a refrigerator, but it will keep cellphones, lights and a radio running.