Google is already working on the fourth-generation Pixel handset, which is likely launching this October. That means it's simply to early for Pixel 4 leaks, although we do know that the handset will run Android Q out of the box. And a revelation a few weeks ago said that Android Q would receive native support for 3D facial recognition, prompting us to speculate that the Pixel 4 may feature Google's response to Face ID. In the meantime, Google has apparently confirmed a Pixel 4 feature already, thanks to an updated to the Android Open Source Project (AOSP) Gerrit. It's nothing too fancy, but it's still a feature that some people will appreciate.
As you can see in the following screenshot, Google plans to bring better dual SIM support to 2019 Pixel phones, as discovered by xda-developers
Image Source: xda-developers
If you're a Pixel 2 or Pixel 3 user, you already know that your phone comes with dual SIM support out of the box, but one of those two SIM cards is a virtual one — or eSIM. That's a handy feature to have in a phone, as long as your carrier supports eSIM.
The Pixel 2 and Pixel 3 phones support Dual SIM Single Standby (DSSS) technology, which means you can't receive calls or texts on the inactive SIM. Comparatively, other Android devices and the latest iPhones support Dual SIM Dual Standby (DSDS) tech, which lets you receive calls and texts on either SIM card. Finally, there's Dual SIM Dual Active (DSDA), where both SIM slots can be used for calls, texts, and data simultaneously.
The Pixel 3 could support DSDS in the future, but not DSDA because it lacks a secondary radio. But the new additions to AOSP
seem to indicate that the Pixel 4 phones will have at least DSDS tech onboard, matching what other devices can do, 2018 iPhones included.