I had the same issue. I am running HA using docker - perhaps it is different for other versions.
I solved it (with help from comments in this GitHub issue and this community thread) by creating docker containers for Whisper and Piper before adding the add-ons in HA. Here’s the relevant bit of my Docker compose file (see linked community thread for more details):
wyoming-whisper:
image: rhasspy/wyoming-whisper
container_name: wyoming-whisper
ports:
- 10300:10300
volumes:
- /srv/docker/wyoming-whisper/data:/data
command: "--model tiny-int8"
restart: unless-stopped
wyoming-piper:
image: rhasspy/wyoming-piper
container_name: wyoming-piper
ports:
- 10200:10200
volumes:
- /srv/docker/wyoming-piper/data:/data
command: "--voice en_US-lessac-medium"
restart: unless-stopped
Once I had these containers running, I added the Whisper and Piper add-ons in the Home Assistant interface using my Docker bridge network’s IP address and ports 10300 and 10200. They then appeared as entities in the Wyoming Protocol integration.
The rest of the assist pipeline instructions worked fine for me.