Changing the operating system
There are two main uses for the gameboy zero, retro games and video/media content. Typically dual operating systems are used for this functionality, swapping one for the other when necessary. These two operating systems are Retropie (for games) and Kodi (other media content).
Flashing an SD card
If you have Ubuntu then there is an app for this.
Hit the windows key type ‘start’ click on startup disk creator in the top box select the iso of the desired OS and in the bottom select your micro SD card (Be careful to select the right drive here). once it has confirmed completetion eject the SD card and test it in the GBZ. If done correctly the GBZ should boot into the operating system of your choice