Do any of your tours include travel on the Bernina Express?
This board does not reach Rick or his staff directly. Staff members do monitor the board, but for a quick answer to your question, you should contact the tour department directly: https://www.ricksteves.com/travel-help/tours-faq
Harold is correct, but the quick answer is "no." You can see the route of our new Switzerland tour online, or the My Way Alpine tour also may interest you.
On the Italian side, the closest we get is Lake Como. For instance, someone arriving for a Best of Italy tour could fly into Zurich, take the train route of the Bernina Express to Tirano, and transfer there for a train to Varenna, where that tour starts.
all the train info you could possibly want, ever in your life: