Support for Galileo and Glonass was touted maybe a decade ago, but there was never any massive improvement in accuracy. Same story? Even worse, Apple Maps still freezes after I leave a tunnel - I’ve been through at least 3 different models in the meantime.
Why don't you supply a source to go along with your bold claim? Instead, here is the first set of test results I found on google: https://rxnetworks.com/press-releases/test-confirms-that-gal...
It shows that using more than just GPS substantially improved accuracy in challenging environments. Dual frequency GPS should show strong improvements too.