is it possible to have more than one Dashboard in parallel - separated in any way from each other ?
I have one Node-Red-Service installed with several flows for several of my friends (reading data via MQTT and showing graphs) and I would like to avoid that they see the graphs I created for each other ?
You can run multiple instances of node red on different ports. Put the logic in your main instance and then have a number of others consisting of just the dashboard nodes getting their data via mqtt.
Perhaps you would rather have that, but you can't have it. The dashboard gives you a quick and easy UI, but you have to accept its limitations. If you want more then uibuilder is an option, but you have to do a lot more work yourself.