Apple must open iPadOS to sideloading within 6 months, EU says

Do I think side-loading and alt app stores would make iPads and iPhones more versatile devices? Yes.

Do I believe indie devs will be worse off? Unfortunately, also yes.

If you are a solo app developer, you will now have to keep presence on all app stores out there, since if you don’t publish on one then a copycat will. Every store would have its own review processes, fee structures, billing and tax procedures. Since you would need to follow a dozen of those, as an indie operation realistically you will either go under or pay middleman companies a chunk for this—so, in the end, you’ll lose the same cut or more and we’re back to the starting point.

Furthermore, I believe you will have much less protection against plain piracy, which was a big thing in the days of yore until it was spectacularly dealt with by Apple within its mobile ecosystem.

This is why I suspect the primary interests side-loading and alt app stores on Apple devices would satisfy is large enterprises and a few opportunistic middlemen. Entities like Epic, Netflix, who will be able to generate more profit; governments, perhaps; a few publishing companies (think CDBaby for apps) will win small time; some users who don’t want to pay and want to get things for free might be able to get their way; indie devs will be worse off.

1) Users win. The first alt app store didn't even launch and it pressured Apple to change it's review policies TWICE. Once to allow game streaming services, and then to allow game emulators. Hell, even developers won here.

2) How did this play out on every other platform. Sure - piracy exists, but most don't and it's pretty non-impactful AFAICT.

Piracy is not-impactful is not true. The disappearance of indie software that do not depend on a remote server (or that's not software on a remote server) is basically due to the inability to monetize with sales native, stand-alone, software. And that's for the piracy.

In some way, the success of the App Store towards indie/solo developers is because there was a way to sell things without the piracy easily steal your sales.

Yes, I know that "it's not stealing", "it's not theft", etc. Beside the ethical/moral conundrum of piracy, the fact is that it destroys the market for small developers.

There have been various efforts to estimate the effect piracy has on revenue like https://news.ycombinator.com/item?id=15319476 or http://blog.wolfire.com/2010/05/Another-view-of-game-piracy

So depending on product category it might be a large drop (EU study finds -38% displacement rate for books) but it might also be a boost (EU study finds +24% for video games), and it is hard to say in general, since even a 90% piracy rate might only mean a maximum of 5%-10% lost sales (from the wolfire blog post). Either way it isn't at the level of "impossible to succeed".

If we are talking about app stores specifically, I bet a much bigger factor in (lack of) success is discoverability, both because your app is literally hard to find and because app store owners allow a flow of cheap clones to compete with your genuine app.