Hello owiz08
I am happy to hear you are soon visiting our country.
You cannot add your Swiss Travel Pass (STP) to the SBB Mobile app; simply show the STP as PDF or printout together with your physical passport.
The SwissPass is for residents, the Swiss Travel Pass for tourists. Consequently, only SwissPass holders (residents) do have a SwissPass ID. As a STP holder, you do not need a SwissPass ID at all. Use the SBB Mobile app for your trip planning, it contains all timetables of all public transport services available in Switzerland.
In order to book seats for Glacier Express, kindly visit the Glacier Express website:
https://www.glacierexpress.ch/en/travel-planning/prices/
Kind regards,
Roland