They’re basically the steps to debug NuGet package symbols, but I’ve had mixed experiences with them with some packages working, some not.
An alternative solution I’ve heard people debugging NuGet packages with is GitLink tho I’ve not tried it myself.
What works best for me is to Debug build the ServiceStack.sln from the source code on Github then modifying my project references to reference the Debug .dlls in the ServiceStack/bin/Debug folder or if I’m referencing ServiceStack.Server package ServiceStack.Server/bin/Debug.
I build my local clone of ServiceStack Github repo, but you can instead download the source code release of the version you’re interested and build that.