Are there any libre image viewers that can show 2 images side by side fro comparison syncing panning and magnification between the two?

I found MulimgViewer, but it only provides binaries for Windows and no build instructions for Linux:
https://github.com/nachifur/MulimgViewer

@unfa Isn't this what you are looking for? Simply download the source code, install the packages and run the script.