I am not familiar with the pebble SDK or notification API it has. Smart watches usually will display whatever notification the mobile devices instructs it to display.

If you get a push notification on your mobile, I don't see a reason why pebble won't display it. The thumbnail image might be fixed but all the text content will be shown. And FWIW, the entire thing is open source so you can go in an add it, or open feature requests, etc.