Well we have another contestant in the Note ring to throwing their hat in to join Roam Research and Obsidian.
Looks like it was built on MIT and the company offers 30 minute 1-on-1 training sessions. FOC.
It also allows the creation of flashcards and repetitive learning so it is great for students along with built-in citation ability for research papers.
Here is an excellent overview on YouTube
With weekly updates coming out from all three, this is the most exciting software development happening for a long time