I think Amazon already has mastered logistic, and it's a pretty difficult field to get into. Similarly, Apple has decades of experience in hardware now. It is definitely hard to find a sector that is large enough yet under developed.

One example of a new one they're trying is Stadia. Gaming in general is an already large and growing sector, and while there have been some attempt at game streaming, none of been as serious. You can see it will be big by the fact that Microsoft (xCloud) and Amazon (Luna) both also jumped in a year later also.

As far as actual moonshots/X go, I believe they have (or had) a few around energy tech. They've funded quite a lot of research into various fusion tech [1]. They also have a lot efforts in Biotech, may it be with Verily, or just DeepMind doing interesting research, such as solving Protein Folding recently [2].

So I definitely wouldn't say they are lacking breadth, honestly if anything it's hard to remember everything they do, as you pointed out :)

[1] https://www.technologyreview.com/2019/05/29/135179/google-ha...

[2] https://www.nature.com/articles/d41586-020-03348-4