I would be far more interested if they open sourced the hardware of their phones, or at least publish enough information that allowed developers port other operating systems on hardware otherwise doomed to end in some third world landfill.
A month ago, MS announced Project Mu - opening up their UEFI implementation on github. [1] Extending that project to their legacy ARM phones would be the way forward, perhaps.
[0] https://www.xda-developers.com/microsoft-lumia-525-hacked-to... [1] https://blogs.windows.com/buildingapps/2018/12/19/%e2%80%afi...