It does not advertise to be Android compatible and I intentionally disabled everything Android related in my Add-on listing. If you still got it offered for Android, please open an Issue on GitHub with a screenshot so I can file a bug for Mozilla.

The sessions API is not available on Android and "Undo Closed Tab" heavily depends on it. So there is no way to make it Android compatible at this point: https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/sessions#browser_compatibility