After killing 2 large-ish power banks because I didn't use them enough*, I realized I really only needed one to top up my phone when out and about on a long travel day. It really didn't need to power up multiple devices multiple times.
Early this year I bought this small, no cord power bank. I've taken it on 5 trips this year, and it's worked well for my needs. This one is android compatible, but I know there are similar ones for Apple.
https://www.amazon.com/gp/aw/d/B0BMPGQXT9?psc=1&ref=ppx_pop_mob_b_asin_title
Edited to add:
It's small and simple enough to keep at hand at home to use occasionally, thereby extending its life.
*If you read the info that comes with power banks, as I finally did, they die if not used regularly--like putting them in a drawer between trips.