Is this still true in the age of the smart TV? I’ve never looked but always presumed they had essentially the guts of a crappy Android phone with the radio transceivers replaced.

They get apps and updates now so I would’ve assumed some semi-reliable persistent storage. This really doesn’t even need to be persistent; resetting on reboot would be perfectly fine.

I’ve no doubt they would struggle to cache “real” 4K, but at the bitrate most of this 4K stuff is sent at, 1 GB of cache should be at least 5 minutes. Netflix recommends at least 15 Mbps for 4K streaming. Even doubled to 30Mbps, that’s ~4MB/s, or about 256 seconds of content cached per GB.