Android solves this problem by making it impossible for an app to access the storage of another app. No matter how much the Steam app wants to see your crypto wallet's key it is not possible (assuming no Linux exploit).
That's nice, but a cell phone isn't a viable gaming platform for anything but very basic games. And Android, at least in its typical Googled form, has its own set of problems; it's a privacy nightmare.
And despite what you claim it is the most profitable gaming platform. There are lessons you can learn from them.
Skinner boxes of MTX in peoples' pockets is a good business model. The lessons were learned, and gacha games are huge on PC.
The vast majority of "gamers" play on a phone. Would you consider something like Neverness to Everness to be "very basic"? Times have changed