I watch my TV alot during the nights in the dark and the brightness is always too much for me, even at 0%

So after a long time of searching on the internet and trying different apps. I've finally found one that actually works in Android tv

https://play.google.com/store/apps/details?id=nu.lower.brightness

'Lower Brightness Screen filter' It's not available on Android TV play store. So download it on your phone and transfer the apk to your TV. Install it. Grant it the permission to draw over apps.

Then open the app and adjust the slider as per your requirement.

The app won't show up on the homescreen so I'd recommend using 'sideload launcher' app.

Works really well on my Sony 49" x8000g It's not the most convenient simple solution but it's the only one that I've found to work.