In order to extract the required WhatsApp archive messages.db you need to unlock your Windows Phone, because the standard WhatsApp backup (on SD or OneDrive) is encrypted.

Requirements: any Lumia Windows Phone with Windows 10, excluding x50 (like 550,950/XL)

Below the steps to get down to this, please follow them closely, you just need your Lumia!

  1. Install 8 Zip from Microsoft Store
  2. Install Interop Tools to unlock Lumia
  3. Create WhatsApp backup with App Data Manage Tool
  4. Extract messages from WhatsApp backup

As shown in the latest point, once you have the required messages.db just move it on the Android phone (through OneDrive/GoogleDrive/USB) so that it can be used by WinWazzapMigrator!

If you want to migrate media too, kindly take a look in here.

Check if your phone is eligible for Windows 10 update
How to install Windows 10 Mobile update on your Lumia 640, 640XL and others
How to upgrade most Windows 8 phones to Windows 10 (alternative)