Ask HN: Join React.js Open Source Study Group?

I am an experienced back-end developer and have been learning React. I have done a couple of introductory courses on Udemy and feel comfortable with the basics.

I want to create a study group that looks at a sizeable open source React project in order to learn advanced React. The current project I am looking at is Mattermost [1], which is an open source Slack alternative used by Uber.

The idea is to learn from the architecture of a large project and try to contribute to the project. Mattermost recently raised $50M [2] so might be willing to allocate a developer to help teach us if we have a reasonable size group.

Open to other project suggestions as well.

[1] https://github.com/mattermost/mattermost-webapp [2] https://venturebeat.com/2019/06/19/mattermost-raises-50-million-to-advance-its-open-source-slack-alternative/