regarding your question to unity : The unity environment is not used for Studio but only for Vuforia engine. You need to address such questions to the following form Vuforia Developer Portal
Vuforia Studio does not provide direct and supported way to incorporate the Web.GL . So far, I know it is based on tree.js and Cordova which means that there is already Web.Gl inside. You need to pay attention that getting some code to work in the chrome browser will not meant automatically that it will be successful on the mobile devices with Android , IOS and HoloLens
One possible option to extend the display is to use of shaders (GLSL) to get some special effects of the appearance. For this you can use the TMLText widget
Another possible option to customize appearance of widget - is to use some CSS styles
The last more advice option to write some widget extension - means you can add your own widget. So far, I know there is Vuforia Studio Extendibility guide, but I think to have it you need to have a development agreement with the PTC R&D team.
Therefore, used who want to have you own functionality which could not be covered by Studio out of the box functionality – in the case may be the using of untiy3d with Vuforia engine is the better choice but this required high programming costs.