A team within Nokia had Android up and running on the company's Lumia handsets well before Microsoft and Nokia began negotiating Microsoft’s $7.2 billion acquisition of Nokia's mobile phone and services business, according to two people briefed on the effort who declined to be identified because the project was confidential. Microsoft executives were aware of the existence of the project, these people said.
Another person said the idea of Nokia using Android wasn't a part of Microsoft’s discussions with the company about an acquisition, even though that was widely recognized as a possibility.
Windows Phone never fit into Nokia's DNA. It's too closed, too external, too controlled; Nokia had little influence over its own destiny with Windows Phone. It's not surprising that many of the brightest minds in the company left in the wake of the Windows Phone announcement (such as the team now at Jolla).
Nokia should have gone Android.