A simple way to do this is to create a custom node from out-of-the-box nodes from Dynamo.
First, select all the elements from the category Levels, use the Level.Elevation node to get the elevation of the levels. Compare this with the imput of the elevations using the == Operator node.
This will create a boolean expression (True/False). This you can feed into an if operator, and you can create variations of this for showing level name, level elevation and imput elevation etc.
in this example, the first level in my project is at elevation 0mm, not 1500mm, hence the null value.
Hope this is what you’re looking for, you can select the nodes (except the code block (list of your elevations) and make a custom node from these.