@weLees apologize for this long discussion but we are trying to help you follow the best practices for snapping your application.
It is not correct to grant the wide access to /proc, /dev etc without really understanding why you are not able to make your snap work using the suggested interfaces. Can you please try to use them and share here the AppArmor denials you are seeing? This will be very helpful for us to get a better understanding and hopefully help you make your snap work the correct way.
If this helps, this is a recent application we have granted declarations Approval request for list-filesystem - lfs and is able to list drives utilization by plugging some of the interfaces we have suggested.
Thanks!