ASK HN: The 20% of 80/20 Current Pain-Points

When thinking of the 80/20 rule applied to development, what are some of your current pain-points in that last 20% of finishing a feature? I’m on a small team who for the next 5 weeks will be trying to make an open-source tool or library to help other developers. We’re thinking of focusing on GraphQL / Apollo, or possibly something to do with Vue. Onward.