@andyross
The Netflix app on Windows 10 or 11 has a lot of content in 21:9 with 4K + HDR/Dolby Vision, if you have the premium plan that supports it.
The two keys are that ALL monitors connected to your computer must support these resolutions + HDR (3440x1440 will play 4K content on Netflix) and have to all have HDCP 2.2 cables connected. The other thing is, you have to get it to work initially with HDMI, for some reason it won't do the initial handshake on Display Port cables, after you get it once (check in the app pressing Ctrl + Alt + Shift + D and look at the resolution plus the video codec (should say HEVC with HDR in parenthesis), then you can switch back to DP cables.
Get more info here: https://www.reddit.com/r/nvidia/comments/la72c3/1440p_ultrawide_and_4k_hdr_netflix_on_windows_10/
I was looking at buying one of these Roku Ultras for getting other apps in 4K + HDR, as I think Netflix is the only major streaming service offering it on a PC (took them years to get 4K + HDR + 21:9). Some good examples of this technology are Rebel Moon, Super Mario Brothers, Our Universe, All Quiet on the Western Front, etc.
There are tons of non 21:9 HDR + 4K options, but you'll have to sort through to find the Ultra Widescreen examples, note: they aren't always listed properly on the app (Super Mario Bros doesn't say it's 4K or HDR and it's both) and they don't mention aspect ratios in those details. A lot of Netflix's major films and shows are in Ultra Widescreen though, almost all of the latest films are.
