How can I export all M365 data to disk before shutting down operations?

I have a client who is closing their law practice and wants to end their M365 subscription quickly to save on ongoing costs. They need to retain important data such as emails and SharePoint files for future reference or to pass on to other attorneys. I'm thinking of creating an archive on an external disk, with two main folders: one for emails and one for SharePoint. In the 'Email' folder, I'd like to have a .PST file for each mailbox, and in the 'SharePoint' folder, I'd want to include all data from each SharePoint site. Is there a tool—either from Microsoft or a third party—that can help automate this process instead of manually copying files? Right now, I'm testing eDiscovery in Purview to create PST files from certain mailboxes over the last 10 days, and I plan to explore SharePoint based on that.