Wassup y'all. I've made the Xbox app to work on the Android TV.

Straight to the business: https://gofile.io/d/5POePT (will be probably gone in a month, there's a copy here in Russian but you'll need to register).

You'll need an Xbox controller and probably a wired/wireless mouse or something that acts like a mouse with a pointer on the screen. Just a remote with buttons won't let you to click through the initial authorization. You'll require just a controller once you've authorized.
Get a mod and the ATV apk to add the shortcut. I've only tested the v7a build, it works.

How to patch the APK yourself

Get the apk for your ABI. You can use this (broken for now) or apkmirror. Unpack it with apktool, get the assets/index.android.bundle . Decompile the bundle using hbctool . Open the instruction.hasm, find Function<getDeviceType> there. Take the function identifier, the "Tablet" string identifier from the LoadConstString (UInt16:123456) instruction and make the function to look like this:

Function<getDeviceType>27302(1 params, 12 registers, 0 symbols):
GetEnvironment Reg8:0, UInt8:1
LoadFromEnvironment Reg8:1, Reg8:0, UInt8:3
LoadConstString Reg8:1, UInt16:36526
; Oper[1]: String(36526) 'Tablet'
Ret Reg8:1
EndFunction

Make sure to replace the function identifier (27302) and the string identifier (36526) with yours because they change every compilation.
Once done, recompile the bundle, replace the bundle, recompile the apk, sign it and try sideloading. This will probably be enough.

Shoutouts

https://github.com/cyfinoid/hbctool
https://github.com/bongtrop/hbctool
https://www.reddit.com/r/ShieldAndroidTV/comments/ixb73c/comment/g69x3i7/
https://ibotpeaches.github.io/Apktool/
http://atvlauncher.trekgonewild.de/