Yes, you could create a plugin to produce admin pages that connect to the REST you’ve made for your application, and provide a gui to interact with its endpoints for CRUD operations. It would be, essentially, no different than connecting to any other external api (i.e. a Mailchimp or Google api).
If you are only looking to provide a gui for interacting with your windows application, there may be less constrictive options. (ng-admin comes to mind)
If, however, your application has other tie-ins to a wordpress install (data lookup relevant to some other content management operation for instance), then look into the Plugin Developer’s Handbook.
You may need to create custom capabilities for user roles to manage access to your CRUD operation endpoints.
Also see: Administration menu a page creation.
And of course the HTTP API.