I'm pretty happy with AppleTV except for the walled garden. I want to run Kodi. I do run it via XCode and a dev account but because of the app restrictions it's a 2nd class experience. Looked for alternatives like Jellyfin but the only ones on the app store all appear to spy on what you view.
You should check out Infuse.
Infuse is a better Plex app than Plex is; and it supports Jellyfin and a bunch of other data sources.
It is, IMHO, a platonic ideal of what a “tv-shaped” video player app should be.
Yeah I mean if you want something FOSS this isn't for you, but neither was a Roku which is what I was responding to
I'm not totally tracking what you're saying, Jellyfin isn't exactly Kodi, it's more like Plex, and Jellyfin does have an app in beta for AppleTV but the best way (arguably) to experience Jellyfin, Emby or possibly even Plex on any Apple product is the Infuse app.
I run Plex and am pretty happy. Will likely eventually switch to Jellyfin as Plex is getting lamer and lamer.
Jellyfin's worst aspect is the opinionated file structure. You have to set up folders the way it wants, and then the resulting UI browser is what-you-see-is-what-you-get. Pretty sure it's done this way for automated metadata discovery.
Ideally, this would be designed in two parts: separate the file structure from the metadata discovery mechanism.
I personally want a file structure managed by the OS. Let me make folders and nested subfolders to whatever structure I prefer.
Then make the metadata discovery slightly more manual. Click a media file, click a hypothetical "add metadata" button, and then a simple search box with "is this your movie?" and click apply to import metadata from a search result. easy peasy.
The UI is clearly meant to resemble a typical media app but falls short if the end user prefers, for example, foobar2000's UI.