As a user, I have always been able to run what I want on Apple devices. Most recently I found my kids were seeing bad recommendations on the YouTube app on Apple TV. I did not like the recommendations, or the adverts. I was able to clone Yattee[1] from Github and build it to the Apple TV from my laptop on the couch
Not as easy as side-loading, but also not difficult. Now when you want to _sell_ something like this, you can't. I'm fine with that. Freedom to run code is different from the freedom to package it up and sell it on a platform you don't own
Google makes side-loading hard[2] on Android for exactly the same reasons. They give preferential treatment[3] to big apps to prevent them from starting competing stores
I have the level of control that I like over my devices. I can't install my own OS on an iPhone, but there's great developments on Mac[4]. Given the hardware is now basically identical, this seems OK
[1] https://github.com/yattee/yattee
[2] https://www.androidauthority.com/fortnite-android-sideloadin...
[3] https://www.androidpolice.com/2021/08/30/google-allegedly-of...