This looks like a very interesting project to make a lightweight sftp server, though the dependency on an SQL db makes it a bit harder to install.

Go has a really good set of crypto primitives, an excellent ssh implementation maintained by the core team, and a great sftp server and client library which makes this project possible.

I recently added an sftp server to rclone: https://rclone.org/commands/rclone_serve_sftp/ - this can serve any of the cloud providers rclone support as sftp (or local disk). This runs on windows/macOS/linux too.

It was a joy to add this as the Go libraries are very well thought out and easy to use.