I found out that the out of the box opencv Stitcher [1] class is perfect for that but nobody seems to have made a GUI out of it.
So, I've spent two days making an extremely simple proof of concept of a Qt Gui [2].
The majority of the time was spent trying to use GitHub Action to automatically build an executable...
If you go see in the release section, there is a tag with a prebuilt binary.
[1]: https://docs.opencv.org/4.x/d8/d19/tutorial_stitcher.html