This is the End User help forum for the Browser but I don't think Mozilla will do something like that since they are concentrating on the Browser only. AFAIK

Thomas James "Tom" Seymour said

I'd love to use Firefox on an Apple TV, even if it has to be the fifth generation 4K Apple TV or newer, since it'll certainly work very well with all the apps I use on my black 64 GB iPhone 6s Plus, and maybe an Apple Watch this Christmas of 2019. If Mozilla can make it work on Amazon Fire TV and Amazon Echo, I'm sure they can make it work on Apple TV in addition to those two Amazon devices! One of the many reasons Firefox is my much preferred web browser is that it has the most compatibility and interoperability across operating systems out there, and I'm sure it can work on more!

https://www.macworld.co.uk/how-to/apple/surf-web-on-apple-tv-browser-air-play-mac-iphone-ipad-3590395/

For reasons best known to Apple, there is no web browser available on the Apple TV. Despite the fact that the Apple TV runs a version of iOS there is not a version of Safari designed for Apple TV and there is no substitute web browser available in the TV App Store.

Firefox for iPhone/iPad is more of a shell due to Apple's restrictions on what browser and JavaScript engines can be used on iOS devices. So it is not like Firefox for Android or desktop.

WestEnd said

This is the End User help forum for the Browser but I don't think Mozilla will do something like that since they are concentrating on the Browser only. AFAIK

The Op is asking for Mozilla to make a version of Firefox web browser for Apple TV devices. Not likely to happen.

If not a web browser then what are you thinking the OP is asking for?