Anecdotally, the AppleTV app on smartTVs won't remember what I was watching. Not the show, the episode or the timestamp into the episode.
This has led me to passionately start my own media server again.
Anywhere between $100-$200 will get you a mini PC that you can use to host movies, series, music, audiobooks and ebooks. If you don't transcode the content then there's no need to worry about a GPU. Set it up headless in a closet.
From there you can use a mobile app to connect your phone/tv/any device to it and enjoy an ad free experience without streaming data over the internet.
My TV is a 15in CRT that I connect with a laptop. My phone is a 1st gen iphone se, with apps to stream.
I've found this setup less frustrating (and wildly cheaper) than spotify, appleTV/netflix/hulu, kindle and etc.
The current state of computing is such that I can't justify buying hardware that requires an app to use. If I want cameras, I buy the camera and connect then to my backend. If I want a thermostat, I do the same.
Works fine for me on an Nvidia Shield TV