caddy-ssh VS Win32-OpenSSH

See the article linked in OP for example, Caddy at its core is actually just config management and runtime platform where just about any kind of app can be built on top. It just happens to ship with state of the art HTTP and TLS apps. Third party plugins can add even more, like https://github.com/mohammed90/caddy-ssh which is a fully featured SSH server. And this can all run from a single binary, using Go's concurrency model.

The plans are there! I focused on implementing the absolute necessary parts of every layer before taking round-2 for the more in-depth implementation. I actually have both the linked thread and the article saved aside to study when I'm ready to implement certificate-based authentication. Knowing Gitea already has it implemented, I had plans to study their implementation to know what I'm venturing into. If anybody else is interested in picking it up, please feel free to tackle it! I'd love to see that PR.

I've created tracking issue: https://github.com/mohammed90/caddy-ssh/issues/10

A request for an official answer on CALs for Microsofts' SSH port is about to turn 6 years old:

https://github.com/PowerShell/Win32-OpenSSH/issues/926

I have automated some things "normally" on Windows successfully after installing OpenSSH-win32; https://github.com/PowerShell/Win32-OpenSSH/releases

Are there any other ssh clients that support FIDO2 on windows besides Win32-OpenSSH?

If you're on windows, you need openssh 8.9 to use fido for ssh. https://github.com/PowerShell/Win32-OpenSSH/releases/tag/v8.9.1.0p1-Beta

Unlike Linux, Windows does not come with any tools for setting up an SFTP server. Even FileZilla Server, one of the most popular programs for setting up a FTP server, doesn't support SFTP out of the box. So, are there any other ways to set up an SFTP on Windows? Yes, of course. OpenSSH is a suite of programs for establishing secure connections to the server. sftp-server is one of the utility programs provided by OpenSSH, so this article will walk you through how to set up an SFTP server on Windows using OpenSSH. Originally, OpenSSH was only available on Linux, but Microsoft has ported it to Windows, so you can now use OpenSSH by downloading the zip file from here.

It is mentioned in Win32-OpenSSH's scope that it does not support "VPN Forwarding". Is it the same thing as local/remote port forwarding (ssh -L, and ssh -R)? Can I forward port to and from Windows with Win32-OpenSSH installed on both client and server?

So, personally, I haven't been able to get FIDO2 keys to work at all on Windows, but I didn't try very hard because I'm set-up just fine with GPG for SSH. Apparently there have been a few bugs reported (ref, and linked issue.