After some minor tweaking and additions, the GitLab dev repository for Escargot’s Yahoo! frontend has finally been updated!
If you want, you can also checkout, or download, the files from the ‘feature/ymsg’ branch and test everything for yourself, as long as you have Python 3.6+ and a command-line set up for the occasion. (More detailed instructions on how to do this here)
It is fully working (aside from webcam and voice chat features). Just have to wait for @valtron to put his finishing touches on the current code and publish it for everyone to use.