Shutting down an agency like USAID require congressional approval, but was done by executive order.

Withholding congressionally approved funding for government agencies is illegal.

Sharing sensitive documents from the fiscal service with (Doge) team members who do not have the appropriate security clearances is illegal.

Giving Elon Musk an unofficial seat and allowing him unfettered access to the entire federal government without any congressional confirmation is illegal and basically amounts to setting up a shadow government.

The list goes on...