You don't need the companion app running unless you strictly require certain settings to be set. For example, I have both companion apps installed but neither run because the only feature I use is the "degreenify 90 hz" settings. And because those are the only settings I have enabled, they are applied on boot only as they don't need a background service. So really it's more your use case if the companion apps are running based on your settings. And one of the companion apps (can't remember which one) has a 'keep alive' setting you can turn off if you want to as well.