Based on Dane Mackier's writeup and initial code: https://medium.com/flutter-community/manager-your-flutter-dialogs-with-a-dialog-manager-1e862529523a.
Both versions 3.0.3 and 3.1.0 of get_it worked, but had to be explicitly named in pubspec.yaml.
Due to changes in get_it, the locator has to defined like so in the provided base project:
GetIt locator = GetIt.I;Extended a tiny bit with more variability (namely having either one or two buttons in the popup dialog), to show that this architecture makes doing so easier.