or to manage more complex cases through a GUI we can use an external program named Flatseal, it can be easily installed from Flathub using a compatible store like GNOME Software, elementary Appcenter or Discover. It is also possible to install through the command line:
At the first launch of Flatseal you need to select Bottles from the left menu, then scroll to the Filesystem section and make your choices.
Flatseal > Bottles
We suggest to not expose all your system or home but manually add each directory in Other files. In the following example we are exposing the ~/Games folder from our home (the default location for Lutris windows prefixes).
Exposing the ~/Games directory
Then the Bottles Importer will see the new directory.