No, there were not animal reserves for smallpox. And that makes a huge difference. There are a lot of mammals that can host coronaviruses. We'd have to eliminate it from those animals, also. Things like bats, civits, minks, etc. This is not likely to happen, given the difficulty of inoculating animals.

Smallpox ONLY infected humans. COVID and other coronaviruses infecting dozens of animals.

And genetically they are as different as a worm is to a human.