Can I have Notification audio through speaker only, when using wired headset, or Bluetooth

Can I have Notification audio through speaker only, when using wired headset, or Bluetooth

If you are sending media audio to an audio device, like a wired headset, Bluetooth headset, or Bluetooth speaker,  then the notification will go to those devices.

It may also go through the phone speaker.   This notification audio can be blocked from going to the speaker, but cannot be sent ONLY to the speaker.  To do this would require the system to broadcast an event BEFORE the notification so that SoundAbout (or any app) could switch the audio from the headset, to the speaker, then play the notification, and then switch the audio back to the headset.  

Since this broadcast doesn't exist, there is no way to do this.   Audio can be blocked from going to the phone speaker (an only play through the headset) because it can be set right away, without the need for a broadcast event.

This may be possible if done in a rooted ROM by creating Android settings that send to the output device (only), if the user chooses this option.

The only thing you can do is set SoundAbout to use Vibrate when using a wired headset, Bluetooth etc.