I don't think you'll ever know off the bat if an idea is worth doing. A lot of ideas sound good to you, but there are so many unknowns, like whether you have a suitable audience and whether there's a good ROI.

As an exercise, you could try doing a rough design of a working system to get a feel for how much work it would be. On top of that, you could try imagining all the things that could go wrong and try to predict the likelihood of each. That's what I would do, anyway.