A number of watches will display cgm levels but most need to be near the phone to work, which kind of defeats the object in my opinion.
I changed to apple when dexcom informed me that support for my 6 year old phone was about to be discontinued and now have an apple watch that does "direct to watch" so displays my levels in the absence of my phone, but not 100% reliably. It does however vibrate if my bg goes out of range.... and is reliable if my watch is present.