Windows c# app/service - start on machine login

I have a vpn app that starts on startup/login of a windows server session. I need another app to start only after the vpn connection is established (so we dont have unsecured vpn traffic during the startup processes.). I am thinking you can write a c# windows service. After the machine starts up and a user is logged in it will wait for expressvpn to start and then establish a vpn connection. Im guessing we can use a native networking command to know if its really connected? then we will execute a specific exe on a specific path. would be great to get an installer for this and a ui exe where we can see the exe and path to be able to change it or update it. Changes to it would probably need to restart the service. We are fine with that. App will be run on a windows 10 and windows 2019 server.