After 4 attempts, I finally managed to migrate @homeassistant on a PI4 to the Synology.
The backup/restore works, the trick is to: Backup; Download backup;Disconnect the PI;Install VM in Syno;Change IP in HA to the PI one;Restore;Wait.
Followed this: https://www.youtube.com/watch?v=u8vOxg-SI74
@silvakid @PJFDF @homeassistant at this point my home automations and IoT control is fully triggered with zigbee buttons (I have few things and few automations).