since neither of your devices support the same things you should come at this from 2 angles
f.e. your pixel doesnt show it supports h265 main 10 https://www.devicespecifications.com/en/model/c624541a and my experience with shield i couldn't get opus to work
so you could be having 1 issue on 1 device and a different on the other
try video only and eliminate that from the equation, ffmpeg -i (infile) -map 0:v -c copy (testfile).mkv
f.e. your pixel doesnt show it supports h265 main 10 https://www.devicespecifications.com/en/model/c624541a and my experience with shield i couldn't get opus to work
so you could be having 1 issue on 1 device and a different on the other
try video only and eliminate that from the equation, ffmpeg -i (infile) -map 0:v -c copy (testfile).mkv