I don't know, I visited almost every major european city back when portable GPS devices were not a thing, and I never had a problem navigating. Even now, I almost never use the GPS.
In fact the only time I ever got lost in a foreign city was a few months back in New York because instead of going with my gut I trusted the GPS.
I got lost plenty of times in Europe pre-GPS. I typically had a physical map, but this wasn't always sufficient. You'd simply have to fall back in things like payphone calls and asking strangers for help.
Also in places like Venice and Barcelona that are overrun by tourists, asking for directions disrupts the lives of locals. Imagine being asked for directions a dozen or more times a day. Thank goodness for Google Maps and data plans.
Older parts of European cities can be a bit harder to navigate. I’m thinking the El Gotic neighborhood in Barcelona and Alfama in Lisbon. But one does get used to it after a day or so.
In fact the only time I ever got lost in a foreign city was a few months back in New York because instead of going with my gut I trusted the GPS.