I was really interested in bottom bracket dynamos. But they have not been available here.

Bottle dynamos suck. One of the most evil things to put on a child's bike is a bottle dynamo.

I suppose hub dynamos are quite obvious nowadays. But, what if you wanted to combine a new ceramic rim with a new hub dynamo? Mission not possiblé.

But, there are still some options. Reelight NOVA contactless rim dynamo looks interesting.