Organization of rootfs and usr apps

I guess we have to adopt a unified way for init scripts when a smart object is booting on all kinds of platform. Currently, I’m working on the RPi4 and trying to clean the init script.
Currently based on sysv init, the main script is /etc/init.d/S51agency which set up var environment as well as start all basic scripts for Wifi and BT configuration. Additionally, it starts a script called /root/ which can eventually launch other apps (debugging, tests, etc.)

We will also set up a systemd based environment to stay compliant with a Ubuntu-like distribution such as one built with debootstrap for example.