I had a question about this too. I have been able to see my extension on my phone using the Twitch app occasionally, but for whatever reason the puzzle piece seems to get shown or hidden. For example, like 7 hours ago, I was able to test my extension, but right now I can’t see the puzzle piece.
Some of my friends, however, have been able to test the extension, so I have no clue what causes the puzzle piece to be visible or not.