Don't even use Android TV, casting from my phone is easier. Mostly use TV as UHD computer monitor.
I didn't notice much difference. It's hard to find info on Android TV 9 using Google. Strange results like TV Guide app or Android TV on Raspberry Pi.
Here's the Philips announcement from last year: When will my Philips Android television update to Android 9? | Philips
If you have a Philips Android Television that came with Android 8.0, your television will be updated to Android 9.0 later this year, in Q3 2020. Philips televisions that came with Android 8.0 can be identified by a model number ending in 504/F7, 604/F7 or 704/F7.
It’d be great to have a database of TVs and which OS version the shipped with and when upgrades happen. Also links to the manufacturers policy on updates. This way we could grade the manufacturers and make informed purchasing decisions