HelloImGui and ImmApp use glfw as a default backend. If you wish to use a different backend, it is possible to use sdl2 or pyglet, via pure python backends.
python_backends contains pure python backends for glfw, pyglet, sdl2 and sdl3. They do not offer the same DPI handling as HelloImGui, but they are a good starting point if you want to use alternative backends.
See examples for more information.