This is the nature of snap applications - they are sandboxed by default - and one of the existing unsupported categories for classic snaps (ie if a snap has this requirement it is not deemed a valid requirement for classic confinement) as per Process for reviewing classic confinement snaps is:
- difficulty making strict confinement work
- access to arbitrary files on the system due to developer/user inertia (home and removable-media is almost always sufficient, though personal-files and system-files may be used under certain circumstances.
So unfortunately even if there are use-cases you would like to support where such files are stored outside of $HOME or /media etc, if the snap itself does not actually require access to files from the host system (e.g. from /usr/include or /usr/lib etc like other compilers may) then strict confinement is the best option.