Please, please, please include support for the FITS file format.
As others before me have mentioned, many astro-cameras use this file format for capturing images. It would be awesome, if we could use the stacking feature in Affinity Photo to directly load FITS images and then process them without having to rely on third-party software to stack the frames and save the resulting image in a Affinity-compatible file format.
Thank you for what promises to be a great product.