animated gifs work on mine, I have Verizon. Your right, if you have an unlocked phone, carriers use the "we can't guarantee it will work on our network" thing. I had that problem when I had an unlocked phone on ATT. SO I switched. Recently I received an email from Verizon saying there were changes to my plan when I started using the Duo. It said that they were removing video calling from my plan. I called for assistance and was told they could not change it to add it again because it was not an option on my Duo. They told me to call microsoft. Just for fun I tried making a video call on google and it worked. So it stands as is. The option is removed but still works.
Glad to hear it works for a Verizon user. I was able to see gifs animating in everything but text messages no matter what app / keyboard (because apparently that can cause an issue too) I used.
Since Verizon as no help I called Microsoft and asked them if I could exchange the device and they said there was nothing wrong with my device after all of our troubleshooting so they said they cannot exchange it. So I figured I could just return it and order a new one.
I wanted to switch carriers but got to thinking and with my discount from work and the grandfathered plan I have with Verizon I really didnt want to switch.
So in the end I just returned the Duo. I freaking loved the phone but the people at Verizon who just didn't care about the issue and Microsoft - though tried to help - could not find an issue. I was so sure it was carrier related but maybe it wasn't? Anyways it was such a big hassle and yes, it was that important to me. I interact with young family memebers and we have fun texting gifs all the time.
So I will be on the lookout for a Duo 2 or will try a Duo again maybe some other time.