It might be possible that Pentax RAW images can be converted to Nikon RAW images in some of the professional digital photo editing program. Although RAWs are not commonly converted between each other.
Convert Pentax Digital Camera Raw Image Format to Nikon Digital SLR camera RAW image.
We found 10 software records in the database related to .pef to .nef file format conversion.
Microsoft Windows software - convert pef to nef on Windows
Adobe's professional tools for RAW image management and post-production
Convert from pef file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned pef to nef. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Program used to manage pictures and photos
One of the best bitmap graphic editing program
Fast and inexpensive app for creating impressive landscape images
A complete image retouching program
A professional photo editor and manager for Windows
Photo Manager is digital photo editor and manager for Windows
Apple macOS / Mac OS X software - convert pef to nef on OS X
Mac version of Adobe' professional digital photo editing tools
Mac version of popular digital image editor
Linux/Unix software - convert pef to nef on Linux
A digital photo editing and converting software for Linux