To refine my point, many successful games come to iOS because it is a controlled environment, with negligible piracy. The games come to Android later or not at all, because it is more of a wild west.
As for productivity, iOS has an undeniable platform advantage, and by that I mean tablets. Apple focuses on the iPad but Android tablets are kind of a joke. Here's androidpolice agreeing: https://www.androidpolice.com/2020/04/21/do-yourself-a-favor...
How does that make sense when all of those games were originally developed for the PC platform, which has rampant piracy, even above that of Android?
If you are developing a Nintendo Switch game, you can focus on building a better game, instead of anti-piracy techniques, or futzing with hardware incompatibilities. That's iOS too.
Or you could simply focus on the legit PC market instead of worrying about people who will likely never be your customers.
FTL and Bastion aren't iOS exclusive. Here are links to pages where you can find their Linux versions. Out of curiosity, where did you get the idea that they were iOS exclusive?
Edit: I hadn't previously heard of it, but googling reveals that Slay the Spire is also available on Steam. The steam page says it has a Linux version. That means that all of your examples of iOS exclusives could actually run on a Linux box, maybe even a raspi. ;)
I will counter with the claim that no major, artistically significant games of the past decade have been iOS exclusives. I might even go so far as to suggest that there are no leading iOS-only productivity apps (by leading, I mean better than what you can get elsewhere to the point where there's a major platform advantage, a status conferred to applications like Photoshop and Microsoft Office which used to be Windows-only). That's a claim that you might be able to refute, but I can't think of any at the moment.
https://lutris.net/games/ftl-faster-than-light/ https://lutris.net/games/bastion/ https://store.steampowered.com/app/646570/Slay_the_Spire/