I don't think it was the point of the parent. Sure it's easy to install, but the point is that if an abuser can somehow control your phone and install that kind of app, then they probably won't let you remove it.

I am a (very happy) GrapheneOS user, I am certain that I can install a tracking app on it. I can even easily side-load an abusive app that would be banned on the Play Store...

Like I would totally recommend GrapheneOS because it's great, but I don't think it solves the problem of "a domestic abuser can access your phone by making you give access to your phone".