Comment 6 for bug 1902915

Sorry but I cannot disagree more.
When an application requires an external dependency that's missing, snapd must install whatever is needed to fulfil the requirements transparently.
Maybe the snap can declare this somehow, I don't know, I mostly use debs.

The current situation is terrible from a usability point of view. An end-user expects snap to just work, without any additional dependencies. That is after all the point of using Snaps.
When it doesn't they'll just install the .dep file.