Armada VS Win32-OpenSSH

Similarly there exist systems for giving formal assurances about concurrent C code, but that's not something the language itself offers.

Even there it depends. 'Programming practices' is vague. Even C can be tamed, at great expense, using formal methods techniques. [0][1][2][3] Adoption of such methods can give a solid assurance of the lack of UB, like use of a safe language. Weaker measures, like adopting MISRA C, don't provide such strong assurances (although they can eliminate certain categories of errors), and as you indicate, their real value is a bit more subjective. Mandating a bad programming style could actively make things worse.

[0] https://trust-in-soft.com/

[1] https://www.eschertech.com/products/perfect_developer.php

[2] https://github.com/microsoft/Armada

[3] https://www.microsoft.com/en-us/research/project/vcc-a-verif...

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.