I’ve been using todo.txt for tasks for about a month now—it’s dead simple, supports all the bells and whistles you mentioned; and, with the topydo CLI, you can very easily make yourself a kanban interface using its columns UI. I sync the files with my iPhone and use Todooo on iOS, which works beautifully.

As for notes, I just write simple text files with my favorite editor. Maintaining complex systems of interconnected notes, I’ve found, most often does not pay off for the enormous time investment required (some specific use cases aside); tags, links, etc. I have all found to be superfluous—any kind of grep integration in the editor is all that’s needed for finding things. I write in either markdown or Typst, because basic Typst is essentially the same as markdown anyway, and because I’ve found it very useful to keep notes in the same format I write longer-form documents in.