A quick tip to anyone looking to perform a backup restore on Home Assistant OS: The restore process takes a long time and it will not be obvious how or if it is progressing.
In my case, for a >1GB backup file the process took over an hour on a RPi4, during which HA become unavailable in the browser and all the Supervisor logs said was that “Backup restore started” and “Home Assistant was stopped” for a very long time, which did not make it clear the process was progressing in the background and in fact I thought something has gone wrong and restarted the RPi.
Ok, I dived into the Docs and found, that the Restore Option is not working, if you ran HA in a container (docker). I switched from RasPi to Docker, so that’s the reason why I have no restore button.