Sounds pretty cool, though as others have mentioned it is pretty niche and I don’t think I’d recommend doing this if your goal is earning money, if you’re doing it out of personal interest as a hobby and because you think it is a fun project, absolutely go for it, no harm done in gaining some experience.

The idea of the side scroller would be, to give that application a compelling frontend and to “gamify” these tasks even more

This sounds a bit like hamster simulator, which we used in high school in our “programming” class, the site is in German, but you might the idea. But I can absolutely see how you can make this more compelling.

There is a vim plugin called vimwiki which is pretty much what you’re looking for I think, but if you’re not using (neo)vim this won’t make much sense I guess. Other than that I’d probably just set up a GitHub gist or repo with your doc stuff