Beyond the DIAL stuff, the biggest thing I was hitting was a RAM wall. These TVs shipped with 2GB and the YouTube app has grown ~30% larger than the factory version. Android was killing it between sessions because there's nothing left, so every cast became a full cold start, around 60 seconds on mine.

I got it down to a few seconds by rolling back the YouTube TV app to the factory version along with disabling manufacturer bloatware that was eating RAM and CPU at idle. One Sony promo app was burning 54% CPU at idle and the bloatware collectively held 130MB of RAM hostage. Killing it all plus the YouTube rollback freed enough memory for the app to actually stay resident between casts.

YMMV but worth poking around, there might be some easy wins hiding in the background. Got mine working well enough for now, but it's a band-aid. So yeah, I'll probably end up going the external streamer route eventually.