So this is what I decided to do, bear with me as I step through this for the benefit of someone else wanting to do something similar. Hint, we are going to use the 'exec' node to do the same thing the BigSSH node does. Well, kinda. Also you are going to need the key pair for the server you are going to be logging into and running remote commands on via ssh available.
First drop this on an empty flow. It's just to make testing easier.
deploy and press the inject button. All this does is run a 'whoami' command on the system you have node red installed on. This way I know exactly what user I'm working as. You could then modify the exec command to issue a 'pwd' just for grins to verify what working directory you will be working from when running commands from the exec node.
login to the host that is running node red via the console or ssh if its enabled as the user we got from the above 'whoami' command. Copy id_rsa and id_rsa.pub using what ever means you have to that users .ssh folder. I do it remotely via the scp command.
While still logged in, try to ssh to the Win10 machine running OpenSSH. If you got the right key pair on this client and the remote server, you should connect without being prompted for a password. If not, you need to visit your OpenSSH config and/or verify you have the key pairs generated and installed correctly on client and server. Once you can complete this step, type exit to end the ssh session.
Now go back to your exec node. You could now do something like this in the command box.
ssh username@workstation_running_openssh_ip msg * Test Message From The Beyond
On the Windows 10 Pro workstation I now have a popup message and the return code from the exec node is a big fat 0. Meaning command exited normally.
So, there it is. I know i left out many details, especially concerning the configuration of the OpenSSH server on Windows 10. There are some gotcha's to that one. I can tell you how I did it, if needed. Also generating the key pair can be confusing. But again, I've done it more than once now. It was definitely a convoluted mess. But now that it is done, it is easy to exec remote commands on windows machines using the exec node.