Really appreciate the help!
Why I used a template sensor was based on nothing than my inexsperience. I moved from domoticz and there it is called a virtual sensor. So I searched how to create and then the template sensor showed up.
So based on your remark I’m also able to create a “normal” sensor. Tried searching how to configure a sensor without a reference to a platform, that but still unclear.
And I also figured out that I need the additional add-on when I used an “entity” node to create an entity in HA automatically. However I wasn’t able to get this working either. I installed the extra components but always receive a debug message like:
"Node-RED custom integration needs to be installed in Home Assistant for this node to function correctly.
As I’m unsure if this has to do with the installation or my usage of the entity node and because I only need 1 value (for now) I was trying to create one manually.
This is my attempt from Node Red
