domoticz: no custom menu visable and no plugin pages

Maintainer: @ammubhave @neheb @dwmw2 @stintel
Environment: (ipq806x, Netgear R7800, OpenWrt master)

Description:
I am running a recent (June 25) self compiled master build of OpenWRT on my Netgear R7800 and installed node 12 compiled from here: https://github.com/nxhack/openwrt-node-packages

I also installed zigbee2mqtt via npm ci and python3, mosquitto-ssl and domoticz from via opkg. Additionally I copied domoticz-plugins-manager and domoticz-zigbee2mqtt-plugin to /etc/domoticz/plugins and I also added the plugins on the Hardware page:

From my understanding and from what can bee seen on the screenshots of the plugins github pages there should be a Custom menu in domoticz and a page where I can interact with domoticz plugins. But as you can see in the attached screenshots I don't see anything like that.

However from the syslog I can see that a plugin custom page is being installed

daemon.info domoticz: Domoticz is starting up....
daemon.info domoticz: Domoticz running...
daemon.info domoticz: Active notification Subsystems: fcm, http (2/13)
daemon.info domoticz: Starting shared server on: :::6144
daemon.info domoticz: (Mosquitto) Installing plugin custom page...
daemon.info domoticz: (Mosquitto) Installing plugin custom page completed.
daemon.info domoticz: (Mosquitto) Connected to MQTT Server: 127.0.0.1:1883
daemon.info domoticz: (Mosquitto) Zigbee2mqtt bridge is online
daemon.info domoticz: (Mosquitto) Joining new devices is disabled on the zigbee bridge
daemon.info domoticz: (Mosquitto) Received available devices list from bridge
daemon.info domoticz: (Mosquitto) Received groups list from bridge

And Zigbee Devices become available in the Devices page:

1. How can I interact with my Plugins? Where are these pages / menus: screenshot from domoticz-zigbee2mqtt-plugin github page, screenshot from domoticz-plugins-manager github
2. Are they (Plugin / Custom Pages) supported at all?
3. What python3 (full, light, or base) packages are really necessary?

One more question:
In the config it says:

# CAUTION - by default, /var is not persistent accross reboots
# Don't forget the trailing / - domoticz requires it
option userdata '/var/lib/domoticz/'

4.) What is the suggested solution to get a persistent configuration of domoticz?

No repository file or test is named; start with the domoticz package configuration and the plugin custom-page behavior described in the logs. Check the referenced Python package variants and the userdata setting, then document the supported plugin requirements and persistent configuration guidance or identify the missing integration behavior.