But Amazon does have much higher bit rates than the CBS-AA app, which often looks softer and artifacty in comparison. So, it's a trade-off.I thought about that myself but CBS AA through Amazon doesn't give you Dolby Vision AFAIK.
Very annoying the sound is 2.0 especially when a few months ago it was 5.1
Subscribing to the CBS-AA channel in Apple TV+ is probably the best bet. High bit rate, HDR, consistent 5.1. Unfortunately, Apple TV+ is not available on the NVIDIA Shield.