However, I must respectfully disagree with @claycodes a little here. While this is true, and very good.
"All data is encrypted in transit and at rest."
That is not the same as End to End Encryption (E2EE), as one very important factor with E2EE is the idea that the only parties able to access the communication in its clear text form is the sender and the recipient.
The data is encrypted before entering the communication channel and decrypted after leaving the channel, with no way to decrypt it in between the sender and recipient, and also not accessible by anyone else after the communication is concluded, (that includes admins and systems).
Only the sender and recipient hold the keys necessary for encryption and decryption.
With Chat, one Workspace user to another, Google holds all the keys, which is also why you can read the conversation between your two users in Vault after it has taken place.
Now... most people don't actually need E2EE!
Not even when they say and think they do. They do need proper encrypted communication, though.
For that Chat and Meet (AFAIK) does the trick). Encrypted communication, impossible for an outsider to access.
Even Gmail, with Hosted S/MIME (also not at all E2EE, not even with Client Side Encryption!!!, as someone else hosts the keys - albeit not Google) is encrypted communication, if the recipient also uses S/MIME.
So, you don't necessarily need a third-party system to be compliant. You just need to know what you are doing, and be able to articulate it when some silly security person tries to say you're doing it wrong.
OR... Everyone should always only use proper E2EE systems for all communication! 🙂
Then there would be no signals telling the eavesdropping agencies that this person over here is communicating over an encrypted channel, that looks suspicious.... 🙂
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Personally, I moved my entire family, children, siblings and parents over to Signal a few years ago, when Facebook tried to force all WhatsApp users to have an FB account, which my father didn't have. Signal is a true E2EE service, for both individual and group communications. Not quite suited for organisations with hundreds of thousands of user, though, and not integrated with Docs and Sheets. 🙂
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https://wheretofind.me/@NoSubstitute