Google's two most recent phones, the Pixel 5 and Pixel 4a 5G, both support 5G connectivity and Dual SIM Dual Standby (DSDS) feature but not both at the same time. If you enable DSDS, you lose the 5G connection. As the company explains on an official support page, your connection is limited to 4G LTE networks when DSDS is turned on. That appears to be changing soon though.
A recent code change to the Android Open Source Project (AOSP) for "Bramble," aka the Pixel 4a 5G, claims that the device can now "connect to 5G network in DSDS mode". This change apparently came from Google's internal Android code, suggesting that it's official. Otherwise, AOSP is open source and allows contributions from all developers.
Though there's no specific mention of the Pixel 5 (Redfin, as Google calls it internally), this ability to use 5G and DSDS simultaneously should be coming to the new Google flagship as well. The two devices have a great deal in common, from using the same processor to having the same camera sensors and more, so much so that Google uses a common baseline for the code of the two devices. And since the recent code change hails from that very common code, it should cover the Pixel 5 as well.
Dual SIM Dual Standby will now work with 5G networks on Pixel 4a 5G and Pixel 5
Google has been offering DSDS capabilities on its phones since the Pixel 3a. With a standard SIM card and an eSIM, users could receive calls and texts through one carrier while using data on a second carrier. However, this ability was limited to 4G LTE networks. As a result, the 5G-capable Pixel 5 and Pixel 4a 5G couldn't make use of this highly useful feature on the newer and faster networking standard.
Now, as suggested by the code change to the AOSP, they may soon gain the ability on 5G networks as well. The support could roll out with the December 2020 Android security patch at the earliest.
The Pixel 5 has been in the market since last month while the Pixel 4a 5G only recently went up for pre-orders. As said earlier, the two devices run on the same Qualcomm Snapdragon 765G chipset. They also pack the same camera setup both at the front as well as at the back.
However, the former is a more premium model and comes with some high-end specs including 8GB RAM, IP68 dust and water resistance rating, Gorilla Glass 6 protection, metal body, wireless and reverse wireless charging, and more. Check out our Pixel 5 review for more.