As was done by @jamesh for system fonts, I wonder if we could expose to snaps hunspell dictionaries installed on the host, through the desktop interface.
I have just added support for spellchecking to the libreoffice snap, and I can imagine that other snaps might want to do the same. This involves adding all relevant hunspell-* and myspell-* dictionaries to stage-packages, and exporting the
DICPATH environment variable to allow hunspell to locate them inside the snap. This is not ideal as shipping all those dictionaries makes the snap larger, whereas typically on a desktop the user will have installed only the dictionaries that she needs, not all of them.