Apple didn't have to lock users out of installing "unapproved" apps on their own. That isn't for the user's benefit and isn't necessary for apple to have a curated app store.
What would the alternative be - the method of installation is the App Store, and Apple's compliance was removing the public and private presence from the App Store within that country.
Just allow sideloading. It's not hard to not block that. But apple is hell-bent on collecting every cent they can, so of course all app installations must go through their walled garden where they can take their 30%. Anti-consumer behavior at its finest.
Not really. You also need a computer running XCode (i.e. a mac), you'll need to follow the instructions out of 9 rather not obvious pounts and you'll also need to build be app you want to install.
Oh, and of course you won't be able to use push notifications, because Apple.
How? There must be some restrictions or this would be HUGE news and Epic would rejoice.
edit: the apps expire after 1 week and need to be constantly reinstalled. This is abusing an exploit in apple's walled garden that will surely be "fixed".