Racking my brain to try and remember the name and location of a church in Germany that is dedicated to the patron saint of travelers. It would have been either in Frankfurt or southern Bavaria. I remember seeing on a travel video where tourist touched something on the wall at the entrance (could be wrong about that). Any ideas?
I would think that St. Christopher would be the patron saint of travelers.
That said, there are many churches where pilgrims traveling to places like Santiago de Compestela would be stopping points or gathering points. Frankfurt has 3 of those, St. Leonards, Justinus Church, and the Deutsche Ordens church, with St. Leonhard's being the main one, with a Jakob's portal. I don't think this is what you are looking for though?
There are lots of pilgrimage routes though besides the Jakobsweg: the Elizabethen route, Bonafatius route and of course the Martin Luther routes.
Or maybe you are thinking of Wieskirche, in southern Bavaria. It is not dedicated to St. Christopher (as far as I know), but it is a "pilgrimage" church. As far as I am concerned, it isn't that much of a "must-see" attraction. It is just one of many over-the-top, gaudy, Rococo churches in Bavaria.