Ok, your message made it sound like people on Windows or Android could join a Facetime call using Teams or Zoom.Huh?
Facetime to a non-Apple user has been a thing for a while...since 2021. The non-Apple user get emailed/messaged a link that opens a Browser window that enables Facetime; it's not a standard. Is that what you are talking about?
Never used it, but my brother did with my parents while he was deployed.
Join a FaceTime call from an Android or Windows device - Apple Support
Got an Android or Windows device? With FaceTime links in iOS 15 and macOS Monterey, anyone can join a FaceTime call from their web browser.support.apple.com
But... this is still something a bit interesting that I didn't know about. I might try using it to call family members who use Android instead of using Zoom with them...