I was able to do this:
Using Terminal & SSH addon, connect and install Python, Pip and MariaDB-to-SQLite3
apk add python3
apk add py3-pip
pip install mysql-to-sqlite3
But, I don’t know what to do next:
Stop Home Assistant
Migrate the database:
mysql2sqlite -f /config/home-assistant_v2.db -d <database_name> -u <mariadb_user> -p -V --use-buffered-cursors
Replace <database_name> and <mariadb_user> by the database name and user used by Home Assistant
Comment the db_url in your YAML configuration
Restart Home Assistant core.
How do I “Stop Home Assistant”?
From the “Terminal & SSH” add-on, I can execute:
[core-ssh ~]$ whoami
root
[core-ssh ~]$ ha core stop
But then the whole Home Assistant would stop, including my session.
Therefore, I don’t know where to run the “mysql2sqlite” command.
Please if anyone can write down more detailed instructions.
Home Assistant is installed as Proxmox virtual machine.
Thank you.