IrfanView has a quite specific licensing arrangement; https://www.irfanview.com/main_what_is_engl.htm.
It might be of use within https://melfortmuseum.org but it is worth checking.

Your XDPXv17 should handle .nef:
RAW photo import

You can import RAW digital camera files, either by using the Import menu option or just drag & drop the file onto the Designer Pro+ window.


Supported file extensions include: *.crw, *.cr2, *.rw2, *.nef,*.mrw,*raf,*.kdc,*.orf, *.dng, *.ptx, *.pef, *.anw, *.x3f
However there are many different extensions used for RAW files by different camera manufacturers, so if you have a RAW file with a file extension not listed above it's worth trying to import it anyway.
Acorn