I would prefer:

1. Manually review the generated stubs in {stub_dir}
2. Run tests locally if you want (see CONTRIBUTING.md)
3. Commit the changes on a new branch and create a typeshed PR

The CI will check everything anyway, and is set up so that you don't have to run anything locally. This would also be consistent with CONTRIBUTING.md.

Originally posted by @Akuli in #8686 (comment)