According to the changelog for an update that is now rolling out, CBS All Access for Android TV now supports HDR content, though your mileage may vary. We installed the latest update on a Hisense H8G Android TV, which supports HDR formats including Dolby Vision through other streaming services, and it didn't seem to work for content known to be available in that format on other platforms.
The changelog for version 7.3.20 is straightforward and just below:
Includes support for HDR content and badging for premium video features, along with some bug fixes.
Previously, CBS limited Dolby Vision HDR content to platforms like the Apple TV, and only some titles (like the recent Star Trek: Picard) supported it. But, although this latest update claims to add the feature, it isn't live for us in our testing on hardware that should support it, and which does when used with other streaming services like Netflix. The feature may be locked behind some sort of whitelist, and it could work on other devices. (Given the app's 1.6 star rating on the Play Store at the time of writing, it's got more than a few issues.)
If you don't see the latest version available on your Android TV through the Play Store, you can sideload the app thanks to those fine, helpful, and incredibly handsome folks at APK Mirror (hint: it's us).