I simply can't get around Proton's pricing model. A lot of services already work with rclone, which has a crypt backend on top that encrypts everything stored in the cloud. With ProtonMail's current Visionary plan, you get 40GB of storage for $30/mo and with ProtonDrive it looks like you'd get maybe 140GB of storage for $30/mo. G Suite is $12/mo and you get unlimited storage. If you're worried about security, you'd simply use GPG on top of IMAP or Mailvelope.
Would your mother understand the "simply use GPG on top of IMAP or Mailvelope" part? These E2EE products are not for the tech savy users, who are willing to go to the extra mile.
