I recently moved from a paper GTD system to using Joplin for my set-up. It really works amazing for a GTD set-up consisting of Notebooks, Tags, notes and todo items. (When I find some time I want to write a longer forum post about my setup).
Something I think works really well in Joplin is the interal linking system.
E.G. I have a main project note with all information for the project like outcome and such things. Inside that document I can also do Markdown linking to all my "todo's" I have created in Joplin.
That all works great then I can quickly see all tasks needed to be done for the project in one place. However, something that would make it even better (at least for me. :)) would be if todo's linked in Joplin showed the current status of them as well. Is it finished or not.
In the image you see that one of the todo is marked as done and the other one isn't. It would be super cool to see that reflected in the note automatically. Currently I make all these links into todo's and I go in and mark them as done there as well, however, if that would be reflected by the link that would just be magic!