When the Google Pixel 2 came out it was extremely impressive. Despite only having the single rear camera, it beat out everything else on DxOMark and held the position for quite a while. When the Pixel 3 was announced, it also had only the single rear camera. And despite one or two issues with the phone overall, Google made some great improvements with it.
Google has published a blog post on how they taught the Pixel 3 to predict depth for its Portrait Mode. Given that it only has a single camera, and not the dual cameras of other brands, it seems like it wouldn’t be possible, but the techniques used are pretty interesting. And involve a case that holds five separate cameras.