GLVND based libOpenGL.so is not present on every supported Linux, despite that appimage exclude list says so. It should be enough to just link to system specific libGL.so.
@@ -393,6 +393,7 @@ endif ()
find_package(PNG REQUIRED)
+set(OpenGL_GL_PREFERENCE "LEGACY")
find_package(OpenGL REQUIRED)
# Find glew or use bundled version