After having my Fenix watches report 2-4% low on distance, I ended up getting a Stryd foot pod.
A favorite trial run with many switchback and under canopy would always report 3.8 or 3.9 while Stryd consistently reported 4.39-4.42 miles. Well the new Fenix 8 reported 4.41 miles with automatic gps mode. 1st run on this trail but I am very hopeful it measures consistently like my Stryd.
Some good news to mix in with all of this!