Feature Request: Interfaces for some xdg directories (e.g., Downloads)

I am very interested in using containers (Flatpak, OCI, and Snap) to limit data exfiltration in case of a zero-day or other compromise. Snap has a lot of useful interfaces, but lacks fine-grained control over home directories. Flatpak does allow very fine-grained control over directory access. Apparmor and SELinux (obviously) do as well.

I suppose there are two possible solutions: 1) add more interfaces to Snap (e.g., downloads, documents, pictures, etc), and 2) documentation/tooling to help us further confine Snaps via Apparmor.

It is important to say, I am NOT advocating that the default for, say, Firefox be “downloads” instead of “home”. HOWEVER, those of use who are more security focused, would greatly appreciate being able to disconnect home and connect downloads, with Firefox for example, as this would greatly reduce the risk of data loss and increase security.