I use irlTV. It integrates with Live Channels so everything shows up in the native guide and all the built-in features like pvr, language selection, etc. work. Dev is super responsive.
https://play.google.com/store/apps/details?id=by.stari4ek.tvirl&hl=en&gl=US
Couldn't find the answer to this so I downloaded the app notifications for android TV https://play.google.com/store/apps/details?id=de.cyberdream.androidtv.notifications.google&hl=en_US and set it up to do so. My desire initially came from wanting my doorbell alerts to pop up on the tv when it sensed movement. I set it up to only follow alerts that contain the right criteria. It was a little bit of a pain. Hopefully someone can come up with something better. I'd love to know as well...
I've looked at this one a few times but its mostly outside of the U.S. It takes HDMI and does a pixel match to dynamically control the backlight or you can put it in music mode.
https://www.amazon.com/DreamScreen-4K-TV-Backlighting-Kit/dp/B07JJFZ2KC
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Very mixed reviews. Nothing to get excited about, especially for the money but would be nice to find a quality equivalent. There are way too many cheap renditions online that under-perform.