You can use Growl for Windows for this. You'd need growlnotify to send the message and the full application where you receive the notification. As per the comments you will need a plugin for native toast notifications.
On the receiving end, you will also need to enable notifications from other PCs and to set up a password.
We're assuming the system where the full GFW package is installed is 192.168.1.110.
On the sending end
growlnotify.com /r:"test1" /a:"test1" /host:192.168.1.110 /pass:test boo registers the application. You need to do this once I prefer the batch varient here cause it has more useful warnings for initial setup. You can switch to the exe file once you know things work.
and something like
growlnotify.com /n:"test1" /a:"test1" /host:192.168.1.110 /pass:test /t:title message would work after that to send messages.
For anything else, you can probably refer to the docs and hack together something to fill in the message content.
Tested between two windows 10 systems and it works for me.
If you want to send messages from linux to a GFW or growl for mac instance, you can use gntp-send