GE-Proton, the unofficial Proton variant by GloriousEggroll, is now also available as a standalone AppImage in version 11-11.
The proton-appimage project by PerseidLab packages GE-Proton releases as self-contained AppImages that run Windows games on Linux with no Steam required. As with the AppImage for version 11-10, the build follows shortly after the actual release. The changes in version 11-11 are covered in the article on the release.
AppImage build of GE-Proton11-11-x86_64. Source: https://github.com/GloriousEggroll/proton-ge-custom/releases/download/GE-Proton11-11/GE-Proton11-11-x86_64.tar.gz

Source: GitHub