Reading the comments from that article is a prime example of how a cult functions.
In reality this will have a 0,002% impact. Most phone users are tech-illiterate and have no idea how to use their devices. You expect these people to go to a different store?
On Android you can have other app stores, why don't you have? Because Play Store is default and all app developers want to be where most users are, not on a 3-4% user share store.
It will most likely be background noise in the first months and everyone will go back to the App Store. The only people that will use an alternate store will most likely be the same ones that use F-droid, so 0,002% of the users.
But hey, it's better to scream how this whole thing is making their devices less secure, because Apple told them so.
I would rather have a “all users must have root access to their devices” or all software must be user replaceable integrated into the law. We let Apple do their own thing, but adventurous users could try installing android and such on the iPhone (similar to how the asahi project is making Linux on M series macs a reality)
Moves like this always assume that location equals citizenship. As an EU citizen living in North America, a move like this means that I would not get the remedy that Apple legally owes me (or would owe me if I owned an iOS device)
The main thing I've been sideloading on Android for a decade is a fan implementation of the Dominion card game called Androminion. It was trademark cease and desist removed from the Play Store a decade ago, but you can still get the apk on Github
There's a couple other things. One big gap in both the Google and Apple stores is the complete absence of adult content. I'm amazed there's not more of a clamour for adult apps among either userbase, given that most people don't own a normal computer. Sideloading could plug that gap