Yes, in principle. Nikon G-type lenses use a spring-loaded aperture lever on the rear of the lens, so if that lever is physically held in the wide-open position, the lens can be used wide open. One crude community-tested method is to wedge the lever with something soft, such as wood or plastic, so you don’t damage the lever.

A more elegant solution would require some kind of intermediary ring or adapter that mechanically controls the aperture lever. However, adding spacing between lens and camera would act like an extension tube and prevent infinity focus unless the adapter included corrective optics, which would add complexity and likely reduce image quality.

So the realistic options are:

• physically jam/hold the aperture lever open, if you accept a hacky solution
• use a dedicated mechanical adapter only if one exists and preserves flange distance

On an FM2, there is no built-in way to control a G lens aperture directly.