Google Drive does have E2EE (https://support.google.com/docs/answer/10519333 https://support.google.com/docs/answer/10519333) but it might (?) require a corpora

Google Drive does have E2EE (https://support.google.com/docs/answer/10519333 https://support.google.com/docs/answer/10519333) but it might (?) require a corporate account. It severely affects collaboration and sharing which is probably why it's a bit of a niche feature.