This is a version of the end crystal bossbar included in the MuffinHunt Datapack, but self-sufficent!
You are welcome to contribute! Feel free to fork and send a PR, like any other GitHub repo! This is a very simple datapack, and so I don't expect to be adding new features to this datapack, besides updating for support with newer MC versions. But I will consider feature PRs if they come in as well :)
Specifically right now, I need help with a custom pack.png, you can add a PR or a comment on PMC, and I'll release an update for it :)
This datapack is licensed under the MIT License. See the LICENSE file for more information.