The problem is though an OS is only as good as its apps, unless it has some killer feature that can make up for the lack of it. Linux worked because Wine and Proton made the huge back catalogue of windows games work on it, but that’s a different use case from a mobile phone. Bank apps I particular are a bit pain point with how they keep using Google’s features to only work on non modified official android versions. I’m sure you could get browsers and such to work otherwise, and some banks you might be able to use via a browser, but that’s already a big hurdle to get over and sell to people as worth doing for all the other benefits.
The problem is though an OS is only as good as its apps, unless it has some killer feature that can make up for the lack of it. Linux worked because Wine and Proton made the huge back catalogue of windows games work on it, but that’s a different use case from a mobile phone. Bank apps I particular are a bit pain point with how they keep using Google’s features to only work on non modified official android versions. I’m sure you could get browsers and such to work otherwise, and some banks you might be able to use via a browser, but that’s already a big hurdle to get over and sell to people as worth doing for all the other benefits.