Ask HN: Encrypted Storage with File Requests?

We are struggling with sharing small but confidential files (SPII) between us and customers. When we discuss PoC with customer, we usually exchange smaller batch of data, like Excel sheets, encrypted through email. We have S3 set-up for processing any bigger load of data after that.

As you can guess email is not ideal and I really don't like it from a security standpoint. If we try to go directly with S3, the business user is usually not too tech-savvy to get the CLI going.

Giving him a GUI, like Cloudberry, requires involvement of IT department, which as you can guess, takes quite a big of time in any reasonable bigger company and slows the process down.

I looked at Dropbox, Box, SpiderOak, Syncplicity, and Sookasa, but none of them fit the need. Basically I'm looking for a SaaS (preferably) offering that has the following features: * Browser client or support for Windows and macOS * File requests with password support * 2FA to access the files * File residency options or located in Europe * SOC2, HIPAA, ISO or any equivalent security certificate * Access logs and auditable at least on IP level * User-friendly and accessible for non-technical people

Nice to have: * File upload (through file requests) without an account * Zero knowledge encryption and open-sourced

I might just want too much though... Do you have your own solution? Is there something that I can host myself (rather not)?