> An exception is bikepackers, who may prize reliability and runtime over brightness and weight. But then the dynamo we're talking about is $200-$400 and that's not including the light.

No, it's about a tenth of that, light included.

Amazon has the Shimano dynohub for $125. Then you have to build a wheel. You might be able to re-use your rim if it's got 36 holes.

I explored dynohubs in the past, but LEDs and LiPo batteries have really narrowed the gap. In my garage, I've got a super long USB cable that we all use for charging our lights. I've used cheap lights from AliExpress, and they are actually quite durable.

Nonsense. At $20 you'll be very hard-pressed to get even a cheap dynohub alone, and that's before the wheelbuild and the light. And bikepackers aren't going to be satisfied with ultra-low-end wheels, anyway.