Contributing to WordPress Core
If you wish to test the bleeding edge or contribute to future versions of WordPress core, you can use the custom-site-template-develop site template. Visit the github readme for the custom site template develop to see more information about parameters and options, including examples.
Note: For everyday client work, such as plugin or theme development, use a normal site template. This template is for contributor days, and testing/patching WordPress itself
The default VVV config comes with a disabled site that uses this template, just change skip_provisioning: true to skip_provisioning: false, then reprovision VVV.
Contributing to WordPress Meta
There was a meta environment maintained by the WordPress team, but it’s unmaintained. For more informatiion as well as its replacements, visit the meta-environment github repository, or ask in the meta channel in the WordPress slack.