A Resetera user was at GDC and at the Microsoft booth they saw a Nintendo Switch. When asked the people in charge of the demo said that they were working on an SDK that would work on Xbox, Windows, Android, iOS, and Switch. They followed up with the fact that MS pitched this idea to Nintendo and described them as extremely enthusiastic and very supportive.
What does it do? It was originally designed as a voice to text accessibility feature, but ended up expanding to include leaderboards, matchmaking, party, and server/lobby support. Microsoft intends to sell the SDK to developers to help them with jump the hurdles of cross platform play.