Microsoft has been making continual improvements to the Surface Duo emulator for developers, and it has now released an update with support for using a keyboard in all postures. There's also new support for searching the Android 'app drawer', plus improvements to notifications. True, the Surface Duo isn't 'Windows', but it is heavily Microsoft-centric and would make a natural upgrade for a heavy Lumia user - the Duo is due out in late summer 2020.

From the official changelog:

What’s new in updated build 2020.429.2

• Support for using a keyboard in all posture and flip modes
• App Drawer and App searches support
• Improved Notifications support
• Improved Settings and quick settings experience to support dual screens
• Enhanced Camera experience (you can access that via the Emulator too!)
• Several platform improvements to better support App Compat around rotation, resizing, fullscreen, and spanning scenarios

We have more improvements planned for future releases, so stay tuned to our blog for future updates.

Download the latest Emulator image

You can access the latest update here. It is recommended that you uninstall the previous version before you download and install the update.

Open source access to Surface Duo samples and helper functions

We are excited to announce that as part of this public update, we are making our Helper Functions, Layouts, and Controls code available on GitHub: http://github.com/microsoft/surface-duo-sdk and open for contribution.

This code, along with our Kotlin and Java samples, helps developers to understand how to build dynamic layouts for dual-screen devices. You can use the issues list to provide feedback. Be sure to check out our contribution guidelines first and we’d love for you to participate.

You can also find the previously published Xamarin.Forms and React Native dual-screen SDKs on GitHub.

I'm going to be grabbing this emulator and reporting back, don't worry.

PS. See also Surface Duo... and the future? from me, with a full analysis of the device and OS choice.