Configuration folder

I’m testing several installation methods to create a safe and most of all flexible HA installation. I have a HA installation in a docker container. What bothers me here is that the folder config the HA container stores all HA settings, which is mapped to the folder /usr/share/hassio/homeassistant on the host. (found this our reverse engineering the home assistant container using docker inspect --format "$(curl -s" homeassistant)

The output included

  - '/usr/share/hassio/homeassistant:/config:rw'

However, my /home/pi folder is also synced with either this settings folder in the container or the host. but I can’t discover how. The command findmnt does not show any mount from the home/pi folder.

Does anyone know how this is accomplished? It is just to understand how HA is setup.