In certain Xiaomi phones, I have tested in Poco F1, it is possible to access the second depth sensing camera.
By tapping on the Kernel version multiple times, we can get to phone testing. There, we can access the second rear camera. The zoom level seems to be around 2X in my model and surprisingly it is a colour sensor. No autofocus though, but the depth is set at infinity so the photos aren't very bad.
The only way to save the pic seems to be taking a screenshot, unfortunately.