And to my knowledge it will not be possible to backup “everything”. App developers can specify if their app (data? not sure) can be backed up. When I tried it out some of the apps couldn’t be backed up indeed (sorry, don’t remember which).
But on the other hand, the homescreen was preserved and also several settings I checked (like volume/brightness level etc.)
My conclusion is: it’s as good as it gets for a “normal” user (i.e. when root or TWRP backup are not an option). Even if it’s not perfect.