Thanks for taking the time to reply to each of my suggestions. I had previously only looked up the borderless feature request and the other ideas came to me afterward.
eirk Wouldn't this just basically be full screen?
It is, but it isn't. Yes, this is what full screen offers, but the advantage of "a window that plays a video + optional live chat without any visible chrome" is that I can use Amethyst or any other tiling window manager to create my own grid of live streaming videos. Normally you get one full screen video and some picture in picture support for another. But computers can easily stream and display more than one video feed.
The result, and why I mentioned it might be useful for recording, is that you end up with something like OBS or a telecast system, where your TV is displaying multiple videos at the same time, each loaded in their own webpage, plus maybe other browser windows or research you might be doing in the foreground as the videos play off to one side.
The closest thing I can compare to is how you can have a Google Meet or Zoom call with multiple talking heads plus multiple screens shared and showing at the same time.
It is a way of efficiently using the space on a larger TV to show more content instead of just making the single piece of content larger. Splitting the screen into windows is something historically only computers can do, which is why I switched from using a Fire TV stick or Apple TV to using a Mac Mini inatead. The novel part is using a tiling window manager so the windows never overlap. It works really well on a large display like a TV.
As I understand it, if I buy a new TV they now have a feature where it can display 4 HDMI inputs on one screen, but the TV I have is limited to two. Unlike the HDMI-based split screen layouts, if I use windowing for this task, I can change the layout to include any number of windows.
My current preferred setup is to have up to 8 pieces of content on screen at on time, with 60% of the screen showing up to three rows of two videos (or to be more precise two columns of 2-4 videos or windows), and the remaining 40% has one or two videos or webpages much larger in a primary column on the right. If I see something I want to make bigger, I have Amethyst configured so I can just drag and drop the window to the spot I want it to be in and it switches places with the content that was there. It feels natural to use and opening a new window with CTRL+N or closing an existing window just reflows all the other windows to take up the space without adjusting them manually. If I want to resize a column, I can drag the window to resize it and Amethyst will adjust the column size to match, resizing the other windows in the column. It has glitches, Amethyst sometimes needs to be relaunched from the menu bar option to do that, and relaunching will re-apply the window layout. You also need to use keyboard shortcuts to switch window layouts if you want to display fewer windows, for example, or split the main window into several rows. But it works great all the same.
I recognize that in some ways I am making a feature request to Apple that they should better support OLED monitors with an accessibility or display preference for borderless windows, if we ignore the other existing feature requests and scenarios in this thread. But if you can add an option to go "borderless" as well as "chrome less" that would be pretty cool. (Once upon a time I wrote a Mac app that overlaid an interactive webpage with a transparent background on the macOS desktop, it worked really well. People forget how awesome window compositing can be sometimes. Brings back memories of Winamp skins.)
And I recognize borderless and these other features are unlikely to be added in a way that exactly suits my needs. I will investigate other options. I know that VLC and QuickTime are often borderless or effectively so. My issue might just be with finding a way to display live chat next to the video. E.g. a custom app perhaps or writing my own webview.
The only other option I can think of that wouldn't require a custom webview or web browser is to make a feature request to Amethyst that would draw black borders or bars on top of the usual macOS window borders to hide them from being displayed on the OLED.
But that's a hack. The better approach is custom windows or custom webpage displays that are borderless or capable of cropping their contents. Cropping the content could remove watermarks and logos in the video stream displayed on screen, or perhaps more control over audio inputs/outputs/normalization of audio across windows and tabs. (YouTube has this feature I think but Twitch does not.)
It's far more efficient to do window compositing with the OS than to use OBS, because you don't have to capture window contents to make changes to how it displays. Though as an aside I have often wished to be able to make a screen recording using resolution independent PDF for each frame instead of MJPEG or similar. Bonus points if it recorded all the compositing layers in their own PDF layer so you could make edits to the window layout after the recording. Apple could do it easily because of the intentional historical overlap in data structures used by CoreGraphics and those of PDFKit as I understand it. But that is a different app, sorry, got sidetracked again.
I suppose you could close this feature request and I will continue exploring options in my own time, as a developer. Compared to Firefox, which only had copy paste issues and the occasional unresponsive tab, Orion's custom browsers have crashed repeatedly due to Passkey login issues on Google/YouTube though they did eventually work, somewhat, and playback sometimes stops at seemingly random, but that might be a misconfiguration on my part.
I will have to try focus mode next. I somehow expected it to be like a Reader mode, and replace the currently viewed content, not that it would "focus on the content by removing the chrome" as it appears to do. That sounds fun, it reminds me of back in the day using full screen IE4 to browse the web with autohiding URL bar and status bar that used to only minimally overlap the content.
The advantage of "going full screen inside a window" is that you can show more than one window to multitask, or monitor or watch one thing while doing another, of course. Without extra window chrome showing, that's the important part: the more windows you put on screen, especially tiled, the more the window chrome takes up space repetitively, even though you can only ever interact with one window at a time when you have only one mouse cursor.
Thanks again for your response, for pointing me to focus mode, and thanks for looking up the other feature requests for me! I appreciate that you took the time to reply and look forward to continuing to test Orion and Kagi.