Manually connect snap to interface

I have installed qucs-spice snap, but it does not have access to /mnt where I store my files.
Tried to connect to removable-media, but:

$ sudo snap connect qucs-spice:removable-media
error: snap "qucs-spice" has no plug named "removable-media"

How can I manually allow access to /mnt ?

As interim solution you can do a bind mount into something like ~/mnt… and contact the developer of the snap to have the interface added for a long term solution.

So, it is impossible to add a connection manually?

The plug must be enabled by the developer