Why on earth would MS lisence windows for free to any OEM? AFAIK they lisenced WP for Nokia for a set price, even as there was a kind of cashback-deal where MS paid marketing support fees to Nokia for using it.


True. SailfishOS is heavily customized for use in UE's, and is mainly UX. Nokia does not need anything like that currently.
What I was pointing out is that Nokia has several other OS'es in use (and has had for a long time, mark you), and now when the UE business is sold off to MS there are no ties left there.