I have a Nexus 5X, and have been on the developers program for Oreo from get go.
Initially, there were some problems with pairing and with some of the apps that didn’t fire properly. Also battery consumption was terrible.
Note that this is stock Android (it’s a nexus )
I loaded the (then) new Android app which was published to the beta channel, by opting-in and downloading from the Play Store. https://t.co/c67MVhCjNQ. Subsequently, I loaded the latest Pebble iterations as they became available, and so my system is fully up to date both on the “O” and the Pebble sides.
The beta version was explored on this thread ~ Pebble App and the Android "O" (8.0)
By the time the final pre-release version of Oreo came out all the issues were resolved, and it now works perfectly for me, and battery life returned to normal.
All the apps I loaded still work, as do the watchfaces.