There is also https://github.com/alphapapa/outshine
Which gives you "full" orgmode in comment sections of your normal source code (haven't actually tried it myself).
Overall I think you are on the right track with your goals but, yes, orgmode does a great job of solving them already with a bunch of additional features too.
Also this process is not automatic - you have to navigate to the buffer and close the task when it's done. Also from the that buffer it's impossible to sync outside (GitLab/GitHub) or share your tasks with a team, what is possible with Kanboard if it's running on DigitalOcean/Heroku or simply synchronizes with GitHub.
Literate Programming in the Knuth sense with org-mode file using tangle[0] blocks holding the source code which can be used to generate and build the project, and a combination of regular emacs lisp code and some org-mode evaluated emacs lisp[1] to do whatever automation is needed.
Now the TODOs can be in the org file, which contains the source, and may also have a reference (automated) to the TODO, which when closed with the regular org-mode command (and is generally only two key chords) will remove the comment as well as update your agenda, calendar, kanban, etc.
I have a dev log in org mode. Any thoughts about what I'm working on go there. Including TODOs. It's always open, so there is no open/save/close process.
Of course, I have to update it. But it's just one more file that gets updated. It's not onerous.
Plus, I'm not destroying documentation about my development process. I have used this method since I started developing professionally 15 years ago. I can go back over a decade and look into why I did certain things for a piece of code and how I decided to break the work apart.
The organizing principle of the todo document is problems. The organizing principle of the code is something else -- control, data. Perhaps ideally they would align, but in my experience they don't.