Usually, no: once you stack multiple RAW files, the result is no longer the original sensor mosaic from a single exposure, so it generally isn’t meaningful to export it as a conventional camera RAW. The normal output from stacking is a high-bit-depth raster image such as 16-bit TIFF or 16-bit PNG.

A standard RAW file contains sensor data before demosaicing. After you demosaic and combine images, you can’t truly turn that back into the original kind of RAW data from a camera.

There is one important exception: Adobe Lightroom can merge multiple exposures to an HDR DNG. That output is typically a Linear DNG, which is a DNG container holding demosaiced image data rather than original mosaiced sensor RAW. So it is “DNG,” but not the same thing as untouched camera RAW.

So the practical choices are:

• stack and save as 16-bit TIFF/PNG for quality-preserving editing
• use Lightroom HDR Merge if a Linear DNG output fits your workflow

Programmatically, writing a true camera-style RAW from stacked images is generally not the right goal; writing a high-precision raster is.