You can set a parameter to the type scene variable then copy the variable in the parameter to a variable that the function changes it and then copy that variable back to the supplied variable in the action.
If you only want to set the variable then you could skip the parameter to variable and only use the variable to parameter.
It doesn’t seem to matter what the variable is.
I don’t think it works with global variables but you can use JSON to convert the scene variable to global.
See this post
To convert a scene variable to a global variable in the scene after the function.
You could skip the conversion if you passed the variable name to the function as text parameter and then used it to build a structure name.
I believe this would have the added benefit of being able to use for each child
This would be the action
