OnPlus doesn't currently support sending WOL packets to devices. We do have that feature already in the ON100 firmware. WIth enough demand from our users I'm sure this would be an easy feature to enable in a future release.
While there isn't an explcit button to cause the WOL packet to be sent, creating a cross-launch of any kind to the target device will cause the WOL packets to be sent to it. When we create one of these cross launch tunnels, we send the WOL packets, just in case the device is sleeping. Once you create the cross-launch instance, you can immediately delete it if you don't need it.
Hope that helps,
P.S. It does make sense to offer this as a stand alone feature.