This shows the Igaro-UK D2 dynamo charging unit charging an iPhone X.
Dynamo chargers get power from front wheels with dynamo hubs. We like the D2 charging units a lot as they are tiny, yet loaded with tech.
Here's a blogpost with a lot of information about the D2's:
https://www.perennialcycle.com/shopcast/igaro-uk-d2-dynamo-charging-units-are-here/