The Dexcom G7 (not yet released) is supposed to be able to connect directly to the Apple Watch. The current G6 requires the phone but does have a watch complication that displays your current trend and trend graph.
It is technically possible to connect the Apple Watch directly to the FreeStyle Libre glucose sensors as demonstrated here: https://github.com/gui-dos/DiaBLE
Unfortunately, in this case you need to pay for a certificate for signing the app, build it yourself and so on
To add to this, it can be configured to also buzz your wrist while you’re asleep if you go low (eg at 70) before it starts making noise for a very low alert (eg 55). Really convenient to not wake up a partner. Your phone still has to be in Bluetooth range though.
With the open source app xDrip, any Android watch has been able to act as a collector since G4 days already. With AndroidAPS you can even dose insulin directly from the watch.