We want to migrate from Home Assistant Container (docker-compose.yml) to  Home Assistant Supervised.
The main idea is to copy the /config file from docker container to main Home Assistant Supervised config folder (/usr/share/hassio/homeassistant by default)
To do so, first we need the path to the source /config folder, in my case /root/compose/ha/config
Then we need to know the path to the destination /config folder, /usr/share/hassio/homeassistant using Home Assistant Supervised default installation
The steps are:
- Install Home Assistant Supervised
 - Stop your Home Assistant Container with 
docker-compose stop - Sync config folders using the following command 
rsync -avh --delete /root/compose/ha/config/ /usr/share/hassio/homeassistant/ - Rebuild Home Assistant Supervised using the following command 
ha core rebuild - Now you will have your Home Assistant Container installation migrated to Home Assistant Supervised.
 
I totally agree. This is awesome! This was absurd seamless! Thanks for sharing.