Started porting a few of our libraries over to .Net Core, and as we all know, the configuration handling changed greatly compared to Framework. Previously, we used app.config.transforms to inject the required settings (though I never liked that option tbh), which were then exposed through some static config class that handled type conversion and fallbacks etc (which I also don't really like). But as app.configs are going the way of the Dodo, that obviously won't be an option for the future any more, so I might as well put in some effort to have a nice solution.
So: What is the recommendation on handling configuration for libraries/nuget packages, especially in the context of .Net Core? Also in regard to (it seems to me) not knowing what kind of config the host application would use (ini, json, ...)?