Depends on conditions, how long the trip is, what options you might have along the way ...

In sunny and more southerly California I liked tying a Solio solar charger to the top of my pack, I thought it was worth carrying there. Not so much in Oregon and Washington, not just because of latitude but also more tree cover.

I recently did some tests with a lightweight unit by Energizer that takes two AA lithium batteries, but for my particular smartphone, at least, I wasn't satisfied with the results, nor were the results very consistent ... things just acted kind of wonky. I got some charge out of it, but it stopped charging at one point with the device far from completely charged and an independent battery tester saying that the batteries still had a lot of charge left. Go figure. Anyway, lithium batteries are expensive.

I've not seen any hand cranked units that are good for anything but getting a few emergency minutes of talk time, though it could be that something better is out there (?). There are wind power units, as well, and I've read that folks are working on something that uses biomechanics (your body motion while walking).

Bottom line is that it's still a PITA if you have any sort of power hungry device. The choice the typically works for me is to use a single device (my smartphone is cell phone, gps, journaling device, camera, etc), and carry extra batteries.

But again, the particular dynamics of the type of trips you have in mind, and how weight and price conscious you are, these can impact your selection a lot.