Ask HN: Is there a legal place to buy offline TV movie downloads?

As a matter of principle, my LG OLED TV will never have access to the Internet. Otherwise, I will face forced updates that modify things against my best interest, for example by displaying advertisements. Currently, the entire TV experience is fast and ad-free, so it could be argued that by granting it internet access, it effectively "breaks" or at the very least becomes an inferior product to what I bought.

Now let's say I want to watch a movie on my TV.

I can rent a 4K blu-ray locally for €3 per night and it will work just fine. The Blu-Ray player needs regular online updates and is generally quite unfriendly towards me, the law-abiding consumer, but it works. I've also heard that people have great experience with RARBG, which seems to be a (probably illegal) place to freely download 4K movie clips. Then there's iTunes, where I can "purchase" and "download" movies, but the resulting files won't play on my TV because they're wrapped in iTunes DRM. Also, iTunes vehemently refuses to download 4K movies, so for those I'd be at the mercy of a good internet connection. Now, I've heard that it's technically easy to extract DRM from iTunes to recover MP4, but that's probably illegal again.

It seems like rented Blu-rays are the only reasonable option here, but for convenience, I'd like to download some new movies. But legally. I don't mind the file having DRM, as long as I can get the TV to play it entirely offline. So that means Widevine should be fine, because it's an Android TV. But it seems that all Widevine-based movie services (iTunes, Hulu, Amazon, Netflix) refuse to let me download 4K files. Plus they all insist on having their own shitty apps, which I'm not sure I can access on TV without the internet.

Is there anywhere I can legally buy a video file that can be played offline on an Android "smart" TV?