Yes I remember the early days of Android too! Not only was there less in the way of architecture guidelines, but also there were more "gotchas", and more that the developer needed to do on a lower level. Things are definitely a lot better now.

I agree that further guidance on some of the things you've mentioned would be helpful. In my business, some of these things are covered by "house styles" which we've agreed in advance, and educate developers in as part of the onboarding process.