Completing the last 10% of a project always seems harder than the first 90%. I'm at this point currently with Inbox Flows and yet again, I'm surprised at how long it's taking to get this over the finish line.
Getting the first 90% done is generally more exciting because it involves creating something new and seeing your vision come to life. The last 10% involves less exciting things like creating graphics for OG tags, fixing bugs, and implementing boilerplate features like payments and team management.
Sometimes the last 10% is completely unnecessary. If you're building an MVP or prototype, you don't need to worry about OG tags or team management features. The core that you've already built should be enough to get in front of people. That last 10% will need to get done eventually though, so plan accordingly.