Regarding the use of snapd-control - this is a super privileged interface and so is not generally granted. However, given the nature of the coda snap is to manage the snaps on a device, snapd-control is designed explicitly for this purpose.
Saying this though, snapd-control is not generally granted for such general purpose snaps in the global snap store - instead the use of a brand store / dedicated snap store might be more appropriate. In this case, you would be able to grant such use of snapd-control directly - @edgeiq can you comment?