The above discussion covers the stereo depth / RGB-D aspect quite well, but not the SLAM and 6-DoF pose tracking capabilities in the RealSense T265 tracking camera, one of the definitely killed product lines. Here’s some information about that.
Only some of the products mentioned in this thread have an IMU and even fewer of those provide their own VIO/VISLAM implementation.
ZED 2 has a working VISLAM, but as also pointed out by others, requires rather heavy CPU & GPU capabilities from the host machine. I have not tried ZED 2i yet, but the product website lists, e.g., “Dual-core 2.3GHz or faster processor” as an SDK requirement so it is unclear if it has really improved the situation.
OAK-D and MYNT EYE do not have built-in VISLAM. The OAK-D SDK is of high quality and under active development, while the MYNT EYE SDK seems to be effectively abandoned (since 2019).
In principle, you add a software VISLAM capability to anything with cameras and IMU using Open Source alternatives such as ORB-SLAM3 or LARVIO, but the computational requirements may be surprisingly high and the licensing terms difficult for commercial projects. Also the general production readiness and suitability for embedded systems varies. If 2D SLAM works for your use case, instead of full 6-DoF tracking, there are more options and this may not be an issue.
And then some advertisement: Our company, Spectacular AI, provides VISLAM & VIO tracking capabilities for devices that have the necessary sensors and reasonable computational resources (e.g., Raspberry Pi 4), but no built-in VISLAM. Our accuracy is generally better than what the T265 provided, especially in challenging use cases such as fast-moving vehicles. Here is a demo with an OAK-D + RTK-GPS: GPS-aided visual-inertial odometry on the OAK-D - YouTube. The solution is available as an SDK (commercial license). Contact us at https://www.spectacularai.com if you are interested.