Enables the Raspberry Pi 4 Serial Port. Instead of Device Mode, the port becomes Host Mode for utilization by the Operating System.
You can connect an SDCard and up to two hard disks or USB drives, which are detected as sda or sdb, and they will all have Serial enabled.
Support is provided on the Home Assistant Community forums, here
Hit the start button and observe the logs. Perform a pull-the-plug restart after starting to ensure it takes effect. You may uninstall the Add-On when complete.