This is really cool. It's such a fun project to pursue. I actually spent a few years building a native application for analyzing CS:GO demos, with a fully custom rendered 3D world for Source maps, along with demo parsing, player animations, and the ability to rewind and fast-forward instantly. You can take a peek at it here: https://rewind.site

I saw in your README that you're looking to add source support, might I recommend building off of zik's code? He already is quite far along in rendering Source maps in webgl: https://github.com/Metapyziks/SourceUtils

Best of luck, feel free to reach out if you ever want to connect.