in short, all the promises made by the developers are all words in the wind.
This box must die with android 5

in any case I found this online store .... the z4 here is with android 9 .... is anyone able to investigate?
It would be a real turning point for our box!
https://www.chinaecarts.com/z4-android-tv-box-android-71-rk3368-64bit-octa-core-cortex-a53-cpu-wifi-dlna-2gb-ram-16gb-memory-kodi-p-8834.html
I do think that they have just put there own os on top of normal Android 5.1! Even though it states 9.1? I can't see how they have made this happen, if it's actually official. It would be great if we had the updated Rom for Android 9.1? Just to see if it's legit.
If you notice, they also state that modified firmware blah blah stuff:
Product Notes:
The Android OS version on this device cannot be upgraded or flashed and any attempts to modify the default OS will void the warranty. As a wholesaler, EstoreChina provides no software support, advice, or training regarding the Android operating system and software.
This product comes with premium warranty service. This means that faulty items can be returned for for a new device with shipping costs covered by EstoreChina. For more information: httpx://support.estorechina.com/index.php /Knowledgebase/Article/View/576/18/premium-warranty
So if the 9.1 fw was available, to flash it would be extremely welcome, but sadly, I'm not holding my breath?