I have some information in my nupkg that I would like to include in the consumer\'s application. What is the best way to include a partial app.config directly when consuming
You do this using .transform files:
In NuGet's traditional way of configuration-file transformation, you add a file to your package's content and give it the same name as the file you want to transform, followed by a .transform extension. For example, to transform a web.config file, you create a web.config.transform file. The transformation file contains XML that looks like a web.config or app.config file, but it includes only the sections that need to be merged into the project's configuration file.
check the post NuGet Package Transformations this illustrated very simple.