Hi @ph0llux!
Apologize for the delay. Is it possible for zffmount to set the mountpoint to snap-specific writable directories (i.e. $SNAP_USER_DATA, $SNAP_USER_COMMON, $SNAP_DATA or $SNAP_COMMON) instead?
In general for a snap to be granted classic confinement, they need to fall under any of the supported categories. In this case I believe we should work towards allowing zffmount to work under strict confinement and thus enjoy the benefits of an stable runtime environment.