Show your app's version somewhere users can reach it, usually at the bottom of the settings/account page:
It pays off in small ways. QA always knows which version they're debugging, you can ask a user which one they're on, and if you ship with Shorebird, the patch number tells you whether your patch actually landed.
Here's a drop-in widget. It reads the app name, version, build, and Shorebird patch for you, so you just paste it in and put VersionIndicator() wherever you want it: