what exactly happens if you try to load that image in an older device?
probably because older devices do not have that much memory? You most probably also are using other assets in the app, which use memory…
see also Italo’s calculation in tip 2 here General Tips and Tricks for App Inventor/Kodular
did you try Scott’s canvas scroll examples?
the examples are a little bit older, so you could check, what kind of image sizes Scott used…
Taifun