Several different .pan files exist and some are actually either graphics projects or even pictures, so for these specific formats export or print to PDF does make sense.
Most notably, projects from The Panorama Factory software are saved as .pan files and their content can be certainly exported to PDF format.
Some legacy image formats also used .pan files and with these you might have luck trying out XnView or another picture viewer with huge format support. Print to PDF is always available through virtual PDF printer.
Updated: September 25, 2023