Pairing Bluetooth accessories directly with Apple Watch
You can already use an Apple Watch with an external heart rate monitor and other Bluetooth accessories. However, that has limitations. With most accessories that you pair with your Apple Watch, you still need an iPhone, but with watchOS 8 that is no longer necessary. There will be a new option in the Bluetooth settings to directly pair health accessories. You can then connect directly to your Apple Watch. Apple has hardly paid any attention to this innovation, but it does offer all kinds of advantages. First, you don't need an iPhone anymore.
A second advantage is that apps can now use background refresh. In watchOS 7, it only works properly if the app is running in the foreground and you're actively using the app. However, you can't use a complication with real-time updates. If you want to see the measurements and the live status, you will have to open the app on your Apple Watch manually. App makers have therefore devised workarounds, where you can see the measurement via the Calendar complication on the Apple Watch. But that is not ideal.
In watchOS 8 that will change: then there will be background app refresh for Bluetooth accessories. Complications are then updated in real time.
Why is this useful?
It is especially a godsend for accessories that you use all day, such as blood glucose meters and other accessories for people with diabetes. During exercise you will often have the app you use in view, but with chronic conditions such as diabetes, the app will usually run in the background all day.
Think of the Dexcom blood glucose meters that work continuously. Now the Dexcom G6 communicates with your iPhone via Bluetooth 4.x, after which you can also see the measurements on the Apple Watch. But if you don't have an iPhone or if you sometimes want to go out with only your Apple Watch, you can't see the measurements.
The upcoming Dexcom G7 works with Bluetooth 5.x and may be able to communicate directly with the Apple Watch, so you always have your measurements in view. This also applies to other health accessories that can connect directly to the Apple Watch in the future. For accessory makers it can have consequences for battery consumption.
Apple may tell you more about it during the announcement of the Apple Watch Series 7. The direct pairing of Bluetooth health accessories also works on older Apple Watch models.
It is also interesting to know which partners Apple would like to work with. There are rumors that Apple itself would like to add blood sugar measurements to the smartwatch. In addition, Apple would like to add more medical functions to the Apple Watch.