Applications of this nature typically only require home and removable-media. While this application can read/write from/to anywhere, that doesn’t appear to be core functionality and isn’t typically a reason for classic confinement. If you have more details beyond what you’ve given, please feel free to provide them. Thanks
It is a command line tool but the user specifies the location of the output file, so saying that it is unusable seems overstated. The snap format and store inclusion process is not unlike other platforms in that there are rules and processes for privileged access to the system. Unless there are details missing on why the snap is broken for typical use cases, it seems like the snap should remain in strict mode.
Please note that the snap platform continues to improve with portals (which understandably may not be a good fit for your application) and the more general prompting work. Strict mode should address typical use cases (again, please correct me if that is wrong) and user-driven access to other locations will become available in the future.