The Android Wear Oreo beta is bringing Notification Channels and more, though it's worth noting that this will only be available to LG Watch Sport users as noted by the Android Wear team on the Android Developers blog post detailing as well announcing this new beta software. The Android Wear team also notes that the beta is available for download as of today for any LG Watch Sport users who sign up for the beta, after which they will be sent a link to grab the factory image for the beta software. What's more is that the factory image will automatically be download to the watch, so there isn't much that users will actually have to do short of signing up to be a part of the program.
As for what comes along with the software, as mentioned Notification Channels will be included, allowing users to configure the notifications that come into and display on the watch. Some points to keep in mind with this is that notification channels that are coming from the phone, or as Google puts it, which are "bridged from the phone," will still need to be managed from the phone's notification channel settings. On the flip side any notifications which are generated from Android Wear apps can be configured and controlled from the watch itself, so there will still need to be some interaction from the phone depending on the app that's sending notifications to the watch.
Background limits are also part of the Oreo Android Wear beta, though this in particular is really a part of the software that's meant more for developers than end users. Still, this will end up being a nice change for end users as background limits should help the battery life of the watch, which is definitely going to be a good thing for the user as that should mean less time spent having to charge the watch, and more time actually wearing it and using it. At this time it looks like the beta may be limited to the LG Watch Sport for the duration of the beta, but it's always possible that Google may open up the software to more watch models.