Well, all streaming services that offer 4K basically. Netflix, Prime Video, Youtube to name a few.

Most apps i have tried that have 4k content all work. Last time is tried YouTube HDR wasn't supported my workaround was to cast from my phone to the TV which did support HDR

Prime app a little buggy on my Sony 900F but it does support DolbyVision 4K...just stutters at times. Netflix, Vudu, Youtube and Plex all work great for me

Man you should have held off for a deal on AF9.

The AF9 ships with Oreo and has a processor and GPU that runs circles around the AF8. I also think it has triple the RAM.

Vudu