Just sharing mine. My company customer consist of major international financial establishment.

As some simply can't go with certain open source project due to compliance, we settled with Tectia SSH[1]. Similar story with VPN and other security-related stuff.

Everything is SFTP with them. Even API json response lol

1. https://www.ssh.com/products/tectia-ssh

Linux/Ruby systems used openssh sftp. Windows Server/SQL Server used some POS SQL Server SSIS sftp plugin.