I think about the last thing I would bolt to any engine is a Chinese-made turbocharger. Second last would be a Taiwan-made nitrous kit.
The reason you don’t see more small-bore turbo motors is that turbocharger cost does not decrease much, if any, with size while efficiency certainly does.
As to two-stroke turbos… well, they can be made to work very effectively when fuel can be introduced directly into the cylinder, after the exhaust port closes. Two-stroke turbo-diesels are some of most efficient internal combustion engines out there.