From the landing page:
Tart is a virtualization toolset to build, run and manage macOS and Linux virtual machines on Apple Silicon.
Tart is using Apple’s native Virtualization.Framework that was developed along with architecting the first M1 chip. This seamless integration between hardware and software ensures smooth performance without any drawbacks.
Tart powers several continuous integration systems including on‑demand GitHub Actions Runners and Cirrus CI. Double the performance of your macOS actions with a couple lines of code.
With more than 36,000 installations to date, Tart has been adopted for various scenarios. Its applications range from powering CI/CD pipelines and reproducible local development environments, to helping in the testing of device management systems without actual physical devices.