Just because the game runs well on my Note 8, doesn't mean it will run just as good on a Note 5. Yet they both use Gear VR, how can I set standards or tell others what to expect?
I think you can tick what devices your game supports in your oculus setup pages. The game has to run at 60 fps at all times on all the devices you list else you'll fail technical review. Therefore the user expectation has to be that the game will run flawlessly regardless of their device if it's a device you say your game supports.
The only strategy you can employ is to optimise for the least powerful device you support and then offer progressive enhancements to users with more powerful devices, either automatically or as a user option.