Hi! Microsoft is currently incorporating OpenSSH into Windows. Link: https://arstechnica.com/gadgets/2017/12/microsoft-quietly-snuck-an-ssh-client-and-server-into-the-latest-windows-10/
Let's start using it.
One thing that would be lovely is support/integration with the ssh-agent for private keys
I'm not sure what you are asking exactly. OpenSSH for Windows (server and client) are separate components which can be installed and used as application/service. While we do have the possibility to incorporate external applications (for the client) similar to PuTTY, it's not the same as implementing a component with "managed" development APIs, such as Rebex, for example. As far as I know, there are currently no managed API bindings which would make it hard to use in an application such as Royal TS. I'm wondering what you would expect from such an integration or what is missing the current components we're using. Can you elaborate?