Note the home and removable-media interfaces exist to provide access to the vast majority of use-cases for accessing user-specified files. As such, these should be sufficient in general and so I do not think a classic confinement override is warranted for this snap.
If you still feel strongly about this, you will need to try and provide more justification as per Process for reviewing classic confinement snaps and in particular please outline which of the supported categories for classic confinement that you believe imgcat fits within.