I normally do image sequences binned 1x1 and the fits header includes both binning and x, y pixsz keywords.
I just did a sequence binned and although the header has the binning keywords: scale, focallen, and pixscale - it does not have xpixsz or ypixsz in it. I’m not sure if it was caused by having bin set to be x2 but those keywords are missing. I believe they should be included - and represent the pixel size in microns, including binning.
On a related note - when I just save an image that I have grabbed, I would like it to be populated with all the basic fits info that should be available at the time. I’m not sure why the fits header info needs to be in a sequence to be stored with the image.