So it seems that Roam Research and Obsidian are the best examples of next generation note taking / brainstorming software. Studying these two apps carefully could help us come up with features to add to TeXmacs to support advanced note taking / brainstorming.
Roam research tutorial course playlist:
https://www.youtube.com/playlist?list=PLwXSqDdn_CpE934BjXMgmzHnlwXMy41TC
Also see these videos: