A year ago, word leaked about Project Monarch, Microsoft's effort to consolidate its many different versions of its Outlook mail and calendar product. At that time, as first reported by Windows Central, Microsoft was planning to roll out its so-called "One Outlook" product and strategy in 2021. Monarch is still happening, but now it seems the bulk of the new One Outlook strategy and deliverables will be rolling out this year instead.
Microsoft currently has different versions of Outlook for Windows, Mac, the Web, iOS, and Android devices (based on the Acompli technology it acquired), all of which its officials (confusingly) tend to refer to as plain-old "Outlook." The new One Outlook -- which also is expected to be branded as plain-old "Outlook" once it's available -- will work on the Windows Desktop (Win32/UWP; Intel and Arm), on the Web, and the macOS Desktop. The new Outlook will look and feel a lot like Outlook for the Web, I hear.