I've downloaded the original, newest Raspberry Pi OS image for the Raspberry Pi Zero and added some config parameters so that when you flash it on your SD card, it works with Sideloader straight away,
I've tested in on Raspberry Pi Zero and Raspberry Pi 3.
It works very well with the Sideloader but it could use some changes like lower resolution, slightly bigger text etc. I'm working on that but it could take some time.
I wanted to post the "clean" barebone version for anyone that would like to make their own changes.
Download :
https://drive.google.com/file/d/1UB11ts1i7GciIpP-R4YWRAEl70OJvCjZ/view?usp=sharing
Flash it with this :