I would not spend 2 nights in Chur; I would spend them in Pontresina or Samedan as Sam suggests. But taking the Glacier Express as Sam suggests. Take a look at the rail map of Switzerland and you will see how this works:
https://www.mystsnet.com/en/download/swiss-travel-system-map-en-2023/?wpdmdl=14294&masterkey=63a023c8da36c
However, Lausanne or Montreux to Pontresina with the Glacier Express would be a very long day, and I would want an intermediate overnight along the way. Maybe Kandersteg, or even Luzern if you take the Golden Pass route and then after Luzern connect via the Gotthard Pass route to the Glacier Express at Andermatt. Lots of options.
But looking at your other posts, where you say you have an AirBnb booked in Como, I am wondering if the Bernina Express is a good option for you. That will take you to Tirano and on to Varenna, which is on Lake Como but a long say from the Town of Como. A long ferry ride, or you go by train to Milan and transfer at Milano Centrale to a different train going to Como.
Can you please clarify your plans? There is a better, shorter, equally scenic way to get to Como if that is your destination in Italy.