It seems to me it would be cool if snap packages would be created for example from MESA(Qt, GTK and other) or with something similar. And libraries would be forwarded to the system.
And then you would indicate in your snap package which version of this set of libraries you require. And everyone should do that. Then there will be no copies.
But I don’t know if the snap developers themselves will do that. But that would be the most convenient solution.