Is the goal to build something and learn something from the experience, or try and build something with adoption in mind?

If the former, the answer to your question is always "yes": if there's something to learn and you're interested in that problem space, it's always worthwhile.

If you're looking at the latter, you're essentially building a product. The next question should then be "is there part of what's out there that you're confident you can do differently/better?"