Microsoft has ended Cortana support for Android and iOS operating platforms on March 31, 2021. However, Your reminders, lists, and tasks will be available in the Microsoft To Do app. Microsoft had announced in July that the company will soon end support for the Cortana app on Android and iOS.
The Cortana content that you created such as reminders and lists will no longer function in the Cortana mobile app. However, you can access through Cortana in Windows. Moreover, the Cortana reminders, lists and tasks are automatically synced to the Microsoft To Do app, which is available for free. As of this writing, the Cortana app is not available on Google Play Store.
Microsoft was planning to integrate Cortana with Microsoft Office in a bid to compete with Google Assistant and Amazon Alexa. With the removal of Cortana app, you now have access to Google Assistant, Amazon Alexa and Siri. While you can interact with Google Assistant and Siri via Android and iOS smartphones, Amazon Alexa is accessible only via Amazon branded smart speakers.
That said, Microsoft Cortana app is no longer accessible on smartphones. You will not be able to access previously created content specific to Cortana voice assistant. You will not be able to create reminders, tasks, and lists. You can view them if you work with Cortana on Windows. Microsoft Cortana is currently available only on Windows 10 PC.