For zero drag with lights off there is the Velogical rim dynamo which I have on another bike: https://www.velogical-engineering.co...ation/?lang=en
It runs on the rim, not the tyre as the old style bottle dynamos do, so there is no tyre wear. It is also extremely small and light weight. It is an easy retrofit since there is no need to rebuild the wheel. The only downsides are the cost (still less than SON) and some running noise (where hub dynamos are completely silent).