File sharing with secure cloud storage vs email

Question

To my knowledge there is no "out-of-the-box" end-to-end secure information transfer with email. In the worst case, sending an email is more like sending a postcard through the post office. Of course, the security issue arises if email message contains sensitive information.

Yes, private key encryption and public key decryption may be used, but that requres prior arrangement between sender and recipient and also involves that added cost for digital certificate with recurring costs. File attachments may also be encrypted and again there must be prior knowledge of how decryption must be done.

Use of file sharing with secure cloud storage may address most of the use scenarios with email. Since files are encrypted at rest and transmitted over secure link, this stands in sharp contrast to third-party email service providers over which the user has no control.

With secure cloud storage, sharing a folder once may be used to access subsequent files added without further overhead. The recipients can receive notifications when new files arrive. This in a way is like collaborative working but my focus is with regard to cloud storage as an alternative to insecure email where practicable.

I would like to hear experiences with regard to using secure file sharing like OneDrive. I also would like to guage if I am missing out something with regard to end-to-end secure email services or something equivalent.

Any remarks please?