There isn't "a list of all datatypes" in .NET because it depends entirely on what assemblies your project references - and that will depend on what you are doing, and what environment your app is to urn under.
For example, a WinForms app will include Control, and many classes derived from it: Form, TextBox, ComboBox, and so on.
But a web based app will include none of those, but will include web controls, and so on.
A WPF app would have another set of controls.
Generally, all apps will include these: Data Type Summary - Visual Basic | Microsoft Docs
] but after that, it's implementation dependant.