I invented the following (unofficial) workaround to install the Volumio android app on an Android TV / Box
What do you need:
The Volumio Android phone app.
I downloaded version v2.6.52 from android-apk.org
Volumio 2.652 APK Download by Volumio | Android APK
Copy this on a USB stick.
Install via the Play Store of Android box / TV the app called Downloader
With this app you can later assign the hidden Volumio app shortcut on your Android TV.
Install the app TV App Repo via Downloader
The Android TV / Box is NOT connected via Ethernet, only via WIFI (requirement of android phone - app). Of course the TV is connected to the same network as the Raspberry PI with Volumio.
Of course the Volumio app is not built for your TV/box… deal with it.
Download the Volumio * .apk from the android apk website and put it on a USB stick
On your Android TV go to the source USB and install the * apk on the TV.
On your Android TV go to the -> Play Store -> download + install the app Downloader (from AFTVnews).
Open the app Downloader en fill in the following URL at: GitHub - ITVlab/TvAppRepo: An app repository of Android TV apps
Download the TV App Repo from Git Hub. Select the *apk for ‘playstore’ (scroll down to releases)
Open the TV App Repo App, now you see the Volumio application.
Click on ‘ Create Shortcut’.