I uploaded my custom NSPanel UI because some of you asked for it after watching https://www.youtube.com/watch?v=MCayBntBlqk. The project was released as is and this ui is absolutely tailored to my needs, so I'm not sure if you find it useful. If it fits for you: go for it! But I don't plan any further development or adjustments. If you want this, you have to do it yourself and use my files as a base. But be warned, working with the Nextion display is anything but straightforward and takes up a lot of time.

• Flash Tasmota on the NSPanel (search the net for existing tutorials)
• copy nspanel.be to Tasmota Filesystem
• adjust/copy autoexec.be to load nspanel.be
• Start the Tasmota Console and run the following command: FlashNextion http://openhab:8080/static/fickelui.tft
• Hint: I used the openhab web server to provide the file, but you can use any webserver that tasmota can reach. The Reason you need a Webserver is, that the file is to large to copy on the esp32, so it has to be streamed chunk by chunk when flashing the nextion display
• if the flash process hangs, restart and try again (the display was then oddly rotated by 90°, but normal again after flashing)
• Create a MQTT thing in openhab with 3 channels:

UID: mqtt:topic:aba3b3fea8:d72f7479da
label: NSPanel Haustür
thingTypeUID: mqtt:topic
configuration: {}
bridgeUID: mqtt:broker:aba3b3fea8
channels:
  - id: Command
    channelTypeUID: mqtt:string
    label: Command
    description: ""
    configuration:
      commandTopic: cmnd/nspanel/nextion
  - id: Result
    channelTypeUID: mqtt:string
    label: Result
    description: ""
    configuration:
      stateTopic: tele/nspanel/RESULT
      transformationPattern: JSONPATH:$.nextion
  - id: Buzzer
    channelTypeUID: mqtt:string
    label: Buzzer
    description: ""
    configuration:
      commandTopic: cmnd/nspanel/buzzer

• create a rule in openhab to feed the display with data and react to touch events (see NSPanel.rules)

Hint: I do not use the json protocol from Sonoff to communicate with the nextion panel, but the standard instruction set from nextion -> https://nextion.tech/instruction-set/ e.g.: to change the weather icon to "new mail arrived" you have to send home.weather_icon.pic=57 as plain text to the cmnd/nspanel/nextion mqtt topic. You can also test commands directly on the Tasmota console by typing Nextion home.weather_icon.pic=57