Is there a way to migrate or copy an installed OS to a new boot or different drive??
A: Yes, easy, safe way:
Backup your configuration file. Install exact same XigmaNAS version to DOM as you already have on USB. Since you are now using another MB port, check if device numbers have changed and be prepared to fix any issues. Once any device issues have been addressed, restore the previously backed up configuration. USB stick (your backup in case of disaster) may now be recycled if everything is working well.