Bluetooth Speaker to say notifications

Hi

my need is really simple : say notification through a bluetooth speaker.

  1. The rule works if the speaker is connected by jack.

  2. The same rule works also if i changed the sink to chromecast .

i have changed the setup speaker to the bluetooth in pi settings and the Default Sink is set to system speaker with mp3 support.

i am totally blocked

i am aware of those threads:

so close and so far, waiting for your genius