It seems that magic tap on WatchOS now works for pausing and playing media playing on the paired iPhone from the watch face now. As I recall, it only worked in the "Now Playing" app before, so this is a welcome addition. Does anyone know whether this is a WatchOS 9.4 feature? It's fairly recent anyway.
magic tap on watch
You are right, I am running the latest public release of the watch software on my first generation watch SE and the magic tap is starting and stopping music on my iPhone, as you would expect it to do. I wonder when this was enabled. The magic tap never used to work, but it does now.
Maybe they also fix it for iOS 16.3.1. Does not work all the time.