Does pebble support standard Android notifications?

IIRC (haven't used mine in a while), Pebble handles standard Android notifications, and even have notification actions. It should work from your watch.

I personally accept the requests from my Gear S3.

There is no option to do anything but open on phone on Pebble. See photos.

For other apps, such as my email, I can choose options like "Mark as read" and "Archive," which also appear on the phone notification.

It appears that one might need to use a WearableExtender to add the actions there.

At https://github.com/kryptco/kryptonite-android/blob/master/app/src/main/java/co/krypt/kryptonite/silo/Notifications.java#L159, one would pre-build the approveOnce and approveTemporary actions, and add something like:

.extend(new NotificationCompat.WearableExtender().addAction(approveOnce).addAction(approveTemporary))