The inspiration is OCaml. I've used it a lot, and some of its best features, like sum types, are missing from Dart (and many mainstream languages).
As for the goal, I just want to finish it for now. I don't intend to publish packages in Bullseye, rather just to use it in projects to consume existing Dart libraries.
Here's a year and a half old page describing the Dart VM's internals: https://mrale.ph/dartvm/
Also, here are two examples of different frontend add-ons for the Dart VM, although outdated: https://github.com/thosakwe/bullseye and https://github.com/jvasileff/ceylon-dart