Microsoft released an experimental Android app today called Keyboard for Excel in the Google Play Store. As the name suggests, it's been developed to make typing easier for the Android version of Excel easier, but it can work with any app.
As you might expect, the layout of the keyboard has been "optimized for numbers" with Excel operators given priority. There's a 10-key number layout available and a Tab key so users can quickly navigate between columns.
Microsoft points out that this app is a work in progress and only uses English characters without any support for auto-correct and gesture typing. Keyboard for Excel is the latest app from the Microsoft Garage program, which has released Android apps such the Next Lock Screen and more recently the Picturesque lock screen.