You all probably have FITS Liberator. This is a natural program for XISF files in order to view the image, do an autostretch on it, view the metadata and more importantly convert it to various image types which will also preserve the astrometric solution found by PixInsight and convert it properly into the FITS header for the fits format.
Video on the tool: https://youtu.be/f9wjMPRjUwg
My Site: https://www.setiastro.com/xisf-liberator
