It looks like some people in the thread below have figured it out — we actually have this. You can start a chat both ways; the system will automatically recognize if this person is on Skype for Business or on Teams.
Thanks and let me know if you have any questions.
An error occurred while saving the commentJosh Harp commented
Is anyone at MS going to acknowledge the growing list of people having this issue. Labeling the Idea as "We have this" is not entirely accurate. Its like if you had a Pinto in the backyard that has a blown head gasket and hasn't run since the 90's and when someone says "Do you have a car?", responding with "We have this!"