They’re sized to drive 3W of incandescent lightbulb at some nominal speed, but that doesn’t mean higher outputs aren’t possible with clever power electronics.
They are nominally a constant-current source of 0.5A so that if you put a 6V/3W incandescent bulb across it, you get 6V from it (P=IV). But if you put two of the same in series, you still get 0.5A, the voltage is magically 12V and it's producing 6W. No clever electronics required, though obv it doesn't give the full 6W until you're going slightly faster.
Taking that principle further is a trade-off between how fast you need to go before it gives you the watts you need, and how many watts of your pedalling power you want to sacrifice to not-going-forwards.
(TBH, I'm fairly sceptical about dynamo charging in general. Given the performance of modern batteries, it doesn't seem worth adding complexity to your lighting system for.)
I've used dynamo charging while touring since it was first sensibly available and it's been a life-line on occasion, but I would agree with you. I'd rather have reliable lighting - the IQ-X is notoriously short-lived particularly if it spends long periods in the rain. Cables can be destroyed in a day of bumpy roads/moist conditions. A power bank good for several days now weighs less than my (small) camera.
