First of all if you have a new question start a new topic. You are much more likely to get an answer to your question. Particularly if your first question is solved.
Yes you can use an HTML GUI
Simple example Babylon.js Playground
or dat.gui https://www.babylonjs-playground.com/#NGS9AU#1
or CastorGUI - Babylon.js Documentation
Babylon.GUI is necessary if you are using VR or you want the GUI to be within the 3D world not just overlaying it.