Two-strokes are extremely dirty, due to blow-through of the fuel-oil mixture, incomplete/less efficient combustion due to crude fuel metering, and inability to use conventional catalytic converters (due to fouling from the above two points). But they do afford roughly double the power-per-RPM of four-stroke engines, and a further power-to-weight multiplier due to their simpler design.

AFAIK there's nothing mechanically stopping you from scaling a 2-stroke, but it would very quickly render the immediate area noxious.

But they are simple, lightweight, and easy to shrink.

This is actually a really important point as we are trying to clamp down on VOC/NOx emissions. Ignoring CO2, two-strokes emit way more emissions than cars per unit work. But a 4-stroke engine, in addition to expense, does not lend itself to tools like chainsaws. In theory this engine could fill that niche.