What kind of C# are you writing, is it a compiled exe you're distributing or is there some way to run C# script on windows?

I've done almost nothing with PowerShell due to the brutal syntax, would love to use a nice language like C# or Python for the control structure (logic, looping, etc) and then just calling out to PowerShell when needing to execute a function. Seems like that should be a possibility, although passing data through may be problematic.

You don't need to 'shell' out to call PoSh. You can host it yourself, see https://msdn.microsoft.com/en-us/library/dn569260(v=vs.85).a... Passing data is quite easy, both ways, is just C# objects. This can be convenient when faced with one of those 'Powershell only API' features.

It's a compiled binary (PE). I've read through numerous books on PowerShell and I don't see its value in comparison to using any other .Net language. All namespaces in PowerShell are available in C#/VB/blah so why deal with the annoyance of ensuring that the client has not only the required version of .Net Framework/Core installed, but also the PowerShell interpreter version too? Perhaps it's because PowerShell doesn't require a compiled binary so it can be modified and run without an extra step, and it allows for easy add-ins with the cmdlet interface.

csi.exe runs C# interactively as a script.

You can run c# directly by using add-type in powershell