How to show snackbar after navigator.pop(context) in Flutter?

Instead of Snackbar i would suggest you to use Flushbar plugin for flutter it is easy to use and it'll take care of everything and u can customize it to a great extent . Snackbar needs a scaffold ancestor to work but Flushbar doesn't and it takes care of all the extra stuff itself and provides with ton of cool features.

Flushbar Plugin here

I'm not sure I understand 100% the use case you have but by returning results from screens and passing arguments to new routes, you can work around basically any scenario.

Let's take an example. A is the original screen, then you push screen B. Now you see B, perform some action there, pop it, you get back to screen A and you want to display a snackbar.

When you pop, you can return a result and handle that result from the "parent" screen as described in the "Return data from a screen" cookbook.

When you receive a result, you can either show a snackbar notification, or alternatively (in case there is a third screen), you can pass that result to another screen as argument.