If you are publishing an oam, on Mac you can select the oam, then use "option+click", then select "get info" for total file size.
If you're doing a normal web publish (File/Publish Settings/Web/Publish), when you actually publish the project, Edge will create a "publish" directory with all your files in it. Select that "publish" directory, and use "option+click", then select "get info". By the way- to save physical file size on disc, make sure the "Frameworks via CDN" tab is checked. This will load the various js libraries from the CDN, rather than storing them locally with your project.
It would be great if you could do this same thing when creating an OAM. So you collect the needed HTML files and images, but refer to the cloud-based (Frameworks via CDN) JS files.
Secon Feature Request:
I wonder if there is a way to do the above, but also include the JS files and have it degrade to use them if the CDN version is not available. That way a web app could use the CDN, but a downloaded table app might use the local js. Just a thought.