https://www.cnet.com/news/cortana-and-alexa-courtship-still-not-ready-for-consummation/

And they're likely to remain vague a little longer. Despite originally being promised by the end of 2017 (and announced in August, 2017), Javier Soltero, Vice President for Cortana at Microsoft, says the two companies are still working to, "provide experiences that are great," according to a recent interview with VentureBeat, adding, "but we're not just going to hurry up and ship something."

Stand-alone Alexa may (or may not) be coming to PCs first, as we reported in January at CES 2018. Among compatible systems are several Lenovo models, including the new Yoga 730, currently being tested in the CNET Labs (sadly, the Alexa feature is not live yet). Alexa's universal Windows app will be restricted to laptops with specific kinds of far-field microphones, in order to make for a good voice control experience, but there's no exact date for that, either. Right now it's a toss up whether Alexa's app or Alexa/Cortana integration will land on Windows PCs first.