The original Z5 had (has?) a built-in MPD server. The Zishan “apk” (Android app) was the remote control for this MPD server: you could (still can?) side load the apk on an Android phone and control the Z5 remotely through WiFi…
MPD (Music Player Daemon) is a free, open source music player server, see:
https://www.musicpd.org/
Theoretically, the Z5 could become a whole house music server and integrate with other MPD controllers/app.
Now, I don’t have the Z5 and I have not heard whether this feature actually worked, and how smooth/reliable it was (is?)… It doesn’t seem to be much advertised, and I don’t know if it is still supported, or even included with the latest Z5C.