I’m not familiar with .NET (are you using C#?), but if the language allows you to put portions of code in separate files and then import/reference those files, then you can absolutely use this functionality when writing a Pulumi program.
No matter how you like to participate in developer communities, Pulumi wants to meet you there. If you want to meet other Pulumi users to share use-cases and best practices, contribute code or documentation, see us at an event, or just tell a story about something cool you did with Pulumi, you are part of our community.