This ESLint config is still using the old .eslintrc config system. As of this writing, the new config system is not ready for prime time. The first issue I hit is that @typescript-eslint is not yet compatible with the new flat config system.
You can track the ESLint team's progress on the flat config system here: https://github.com/eslint/eslint/issues/13481
My work-in-progress flat config is in the file FLAT_CONFIG_EXPERIMENT_base.cjs.