You might consider adding a configuration utility similar to what the Raspberry Pi has.
Specifically, what I would like to do, without an advanced level of Linux system configuration skills, is:
- change the default username and password
- require the user to login with the password
- change the timezone (to +8)
- change the language (actually, I don’t need this, but many of your users 寫中文)
- change the desktop manager (in my case, to xfce)
- change the boot parameters (useful for debugging)
- change overscan (if your monitor has alignment issues)
For the RPi see raspi-config (https://www.raspberrypi.org/documentation/configuration/raspi-config.md) and /boot/config.txt (e.g. https://elinux.org/R-Pi_configuration_file).
Edited to consolidate reply.