If you haven't heard it already, check out the concept of a…

If you haven't heard it already, check out the concept of a "Zettelkasten" by Niklas Luhman.
There are special apps for it, but the most platform independent approach would be with simple text-files.
You can try either neovim with some extensions which took me a lot of time, or you try the app "obsidian", which is available for most operating systems and platforms.
Obsidian also has a timelapse feature to visualize the creation of your zettelkasten/mind-map with all its connections.
I love playing it from time to time, its beautiful.