There actually is/was two standards for this in Linux: GNUStep Application Bundles[0] and ROX-Filer AppDirs. Currently AppImage is trying to keep the dream alive, but it bundles the files in a squashfs image attached to the executable.
[0] Which of course came from NeXT Application Bundles, which is also where OSX Application Bundles came from.
[0] Which of course came from NeXT Application Bundles, which is also where OSX Application Bundles came from.