Some time ago, there was a program for the Mac called "Quartz Composer" use for doing some graphic things.
The main thing I'm bringing up here is the interface...

The boxes and lines connecting to them. A simpler one:

When you actually dig into the file that is saved, it turns out to be an xml file.
<key>rootPatch</key>
<dict>
<key>class</key>
<string>QCPatch</string>
<key>state</key>
<dict>
<key>connections</key>
<dict>
<key>connection_1</key>
<dict>
<key>destinationNode</key>
<string>Camera_1</string>
<key>destinationPort</key>
<string>inputRotateX</string>
<key>sourceNode</key>
<string>Interpolation_1</string>
<key>sourcePort</key>
<string>outputValue</string>
</dict>
<key>connection_2</key>
<dict>
<key>destinationNode</key>
<string>Camera_1</string>
<key>destinationPort</key>
<string>inputRotateY</string>
<key>sourceNode</key>
<string>Interpolation_2</string>
<key>sourcePort</key>
<string>outputValue</string>
</dict>
<key>connection_3</key>
<dict>
<key>destinationNode</key>
<string>Camera_1</string>
<key>destinationPort</key>
<string>inputTranslateX</string>
<key>sourceNode</key>
<string>Interpolation_3</string>
<key>sourcePort</key>
<string>outputValue</string>
</dict>
</dict>
<key>nodes</key>
<array>
<dict>
<key>class</key>
<string>QCInterpolation</string>
<key>key</key>
<string>Interpolation_1</string>
<key>state</key>
I'm not going to claim that this the most efficient storage (that particular one goes on for 2465 lines). However, the thing that should be examined is the way to represent the labview in such a way that one could take the text representation and covert it back into a working graph.
Just counting wires as 1 byte is cheap.
While this may be a significant undertaking, consider trying to figure out how to represent the LabVIEW structure in JSON or another structured data language. The necessary thing is to be able to represent the program in text, and be able to convert it back to the same program in LabVIEW via a mechanical transformation. Otherwise, this feels very much like "I'm going to write in C, but I'm going to count if
as one byte and switch(x) { 1: break; }
as four bytes"... which, well, it's not. Golfing LabVIEW according to some scoring system is fine, but calling them bytes and comparing them with languages that actually use characters is like comparing apples and oranges. Call them "LabVIEW Primitives" or "weighted fundamental graphical programming primitives" - but not bytes.
Another (better?) way of getting an idea of how much information is in a given LabVIEW file is to take the save file for it, and compress it with a standard compression program at maximum space efficiency - and that is how big the 'program' is. Its kind of like how the byte counting of the golfing languages can encode things in there.