A few people asking what to use for stitching manually, the best I have found is APG (Auto Pano Giga), it was bought out by GoPro years ago and is no longer avaialble, however check out the most excellent thread started by @clinkadink and download links for it are there.
The thread talks about Kuula’s maximum allowed file resolutuion of 16384 x 8192px, if you use Panoee this can be unlimited ;o)
APG is avaialble in Mac and PC flavours, persoanlly I use the Mac version, but @clinkadink tutorial as well as others on YouTube are exactly the same for both platforms