I recently created a winforms project in Visual Studio 2022 and discovered my own answer to this question, below.

When trying to access an assembly attribute in AssemblyInfo.cs that looks like this:

[assembly: AssemblyCopyright("Some Copyright 2025")]

My call to retrieve this information ended up being this:

MessageBox.Show(
    
Assembly.GetExecutingAssembly().GetCustomAttribute<System.Reflection.AssemblyCopyrightAttribute>().Copyright.ToString()

);

The above message box will read "Some Copyright 2025." Presumably you can call any custom attribute in the AssemblyInfo.cs file in this manner.

This looks fiddly and there is probably an easier way, but to the best of my knowledge, this is the simplest thing you can do to retrieve these.