Not following what you mean because neither Voila or Voici would involve index.html?
It would help to talk specifics here. Voici is the most direct to deploy on GitHub Pages as it is supported and there is a guide. (The newer guide is here. I have used it to make several tests you can access from the link here.) However, while it mostly works, Voici development is still at an early stage and has several quirks. JupyterLite deployed on GitHub pages though is more developed and so if you don’t mind the code showing, it would be a better route for deploying useable strategies via GitHub pages these days. If you can use it, I’d recommend the xeus-python + JupyterLite demo because it supports pre-installing packages and so more stuff will work on start-up for your users without them needing to run install commands. I have used that to make my own repo here where ipycanvas works in sidecar to give a flavor of the possibilities. The guide for the pyodide-flavor of JupyterLite is here. You can try it in your browser using this link to get a feel for the possibilities and approaches needed.
Last I knew Voila wasn’t supported on GitHub Pages because it needs an active kernel and so a static site deployment, like GitHub pages, won’t work. If you want to use temporary MyBinder-served remote machine sessions to serve your repo, you can use Voila though fairly easily. I have several examples working here. The first example under ‘Direct Links’ there should work if you click on it and are patient, as I just tried it and it is confirmed working fine at present. (Alternatively, click here.)
So the two are very different and so conflating them in a single post is just adding to confusion about what you really want help with?