How long between times when you can charge things from an outlet? A few days? Over a week? Over a month?
A few days, get a power bank. More than a few days but under a week, get two. Maybe three.
Longer trips, Gauvins and Happy Feet (he appears to have stopped posting on this forum) were happy with solar panels.
I use a dynohub. I used to use Sinewave Revolution to convert the dynohub output to USB power, but now use a Cycle2Charge.
Here is a post that Happy Feet wrote.
What's the most reliable hardware choices?
I did a two week tour in April this year, was fully self sufficient with a dynohub and USB charger (the Cycle2Charge). That said, my phone is typically off. I use a GPS while riding. Battery powered taillights (two lights, each has a pair of AAA batteries), headlamp for my head (one AA battery), and a camera (Li Ion camera batteries). I carry a AA/AAA NiMH rechargeable battery charger when touring, charge things up with a power with a pass through power bank. And use a Li Ion battery charger for my camera batteries from the pass through battery pack.
If you are a power user, phone always on, etc., you may need more power than those of us making suggestions here.