Hi, is it possible to integrate a webpage GUI OR electron desktop application w/user input with Node RED backend?
Thanks!
Yes.
Have a look at Node-RED Dashboard as just one of many such examples.
If Dashboard doesn't suite, do have a look at uibuilder as well. 
This could be trickier as it depends on whether you have the opportunity to make changes to it or whether it provides an accessible API. Electron is "just" a desktop version of a packaged Node.js app. So if you are able to make changes, you could add an externally accessible page or API that could be integrated.
Or... just make some ajax requests out of your current browser-based applications, which can GET or POST data to node-red endpoints (flows that start with the http in node, and end with an http response node). You can even use these node-red http "urls" in your <img src="..."> elements, for instance.
