To get local speech running, you should install simon-say which is an equivalent of speech-dispatcher that uses the macOS say command to speak.
npm install --global https://github.com/andrewn/simon-say/archive/master.tar.gz
Make sure you have the latest radiodan and run the radiodan manager:
cd ~/path/to/radiodan/services/manager
npm start
In another terminal, run simon-say:
SOCKET_PATH=/tmp/speechd.sock simon-say
Then, in yet another terminal, run the speech service:
cd ~/path/to/radiodan/services/speech
NO_AUTO_SPAWN=yes SOCKET_PATH=/tmp/speechd.sock node src/main
In the speech service directory, there's a test.html file which will connect to the WebSocket broker and talk to the speech service. You can tell it which WebSocket broker host and port to connect to. You'll need to serve the test.html file yourself somehow.
To connect to the WS broker running the locally, you can use something like this: http://localhost:whater/test.html?host=localhost&port=8000
You can then use the text box to speak stuff. Or press "List Voices" and pop open the Web Inspector Console to see the response.