As a side note, you can literally write a C# program and run it inside PowerShell without installing the normal .NET toolchain. Add-Type can accept a string with C# source code and it'll build on-the-fly and load it into your PowerShell environment. And from the C# code you can P/Invoke C functions if you need.
Once you've loaded it up, you can use it directly from PowerShell. I've done this in a pinch and then wrapped it up in a normal PowerShell cmdlet to do things that weren't available from PowerShell otherwise and without needing a .NET build workflow, without needing to store .DLLs, etc. In OP's situation that's what I'd be doing instead of building .DLLs.
Once you've loaded it up, you can use it directly from PowerShell. I've done this in a pinch and then wrapped it up in a normal PowerShell cmdlet to do things that weren't available from PowerShell otherwise and without needing a .NET build workflow, without needing to store .DLLs, etc. In OP's situation that's what I'd be doing instead of building .DLLs.
https://learn.microsoft.com/en-us/powershell/module/microsof...