Please note that the snap’s $HOME is set to
~/snap/<snap name>/<current snap revision> and snaps are allowed to created any files they desire within this directory, so the use of personal-files here does not seem needed. From https://forum.snapcraft.io/t/the-personal-files-interface/9357: “this interface is typically used to provide read-only access to top-level hidden data directories within a user’s home directory in order to support importing data from existing applications where the snap is the clear owner of the target directory.”
Example text for when the snap wants access but isn’t the clear owner: "This snap is not the clear owner but it does seem clear from the application’s intended usage that the application should have at least read-only access to the directory with auto-connection, so long as the interface reference is clear. Please use the following:
plugs: config-DIR: interface: personal-files read: - $HOME/.config/DIR
It is less clear that write-access is required, and if it is, it should probably be manually connected; with read-only access, the snap can import/sync to its per-snap area and not interfere with the target directory which is more in-line for the use of this interface and is much safer and robust. Can you provide more information?
As for /tmp, yes, there is nothing more you need to do.