No notification for Android wall panel running Companion

(First: Yes I’m a complete newbee on HA so no answer is dumb or too easy to mention. And please add some extra context to your answer where exactly certain settings etc. can be found.)

I have side-loaded the Companion app version “2023.3.0-full” into a Sonoff NSPanel Pro (Android 8.1.0) wall panel with WiFi connection. The device does not have Google Play installed and I got a warning about Firebase not working at first time starting up Companion App but otherwise all seems to work just fine. I’m now trying to send notifications from my RPi3+ HA host (v2023.4.1) to that Android panel but is getting an error:
ERROR (MainThread) [homeassistant.components.websocket_api.http.connection] Device not connected to local push notifications
As far as I understand, there is a Local Push functionality that should solve this but I cannot find a single trace of that on my HA host or in the Companion app.
In Companion app when selecting App Configuration → Notification Channels, the only channel visible is “SensorWorker”. Nothing about WebSocket or Persistent Connection can be found in App settings.
The SensorWorker seems to work fine because sensor data from Android is sent to HA host.
(I do have a regular Android phone with a Google Play installed app that doesn’t have any issues at all with notifications.)

Any ideas how to solve the “Device not connected to local push notifications” error?

It won’t work without Google Firebase on your Sonoff

Edit: This video might have some ideas

Sounds like a real bummer to have an app relying on GP Services even if it runs on the same network as the HA host. I found this on Blakadder but is a bit reluctant on starting to fill my poor resource limited wall panel with bloat-ware. :unamused:

Settings > Companion App > select the server > persistent connection

Thank you sooo much!
Notification works now!

Now I just have to find out why the command_screen_brightness_level notification works on my Phone but not the Wall panel.