Send emails from your own Stern alias or from a different address
Import your Google data into another account
For Google Drive files you may wish to directly transfer ownership of the folders and files from one account to the other as that will preserve any shares you might have. Alternatively you can reupload the files to the remaining account.
For email, you would need to import the .mbox file(s) from Google Takeout into Thunderbird and from there copy them into your remaining account. For specific instructions on how to import .mbox files into Thunderbird please refer to https://www.howtogeek.com/709718/how-to-open-an-mbox-file-in-mozilla-thunderbird/.