Nuget doesn't support any sort of local link functionality. This makes local development, where both the nuget project and the consuming project are being locally developed, a real pain. Even after setting up a local package source, whenever a change to the nuget project is made the version number needs to be bumped, the project re-packed, and then the consuming project update to the new version.
To avoid this, an extremely hacky Directory.Build.targets msbuild file can be added to your dev environment. This will affect anything below it in the folder structure on disk, and auto-replace any PackageReference to the specified nugets with assembly references to the local build paths. Then, whenever you build the nuget project, the consuming project will automatically have the changes in it. No need to re-pack, increase the version number, upgrade the nuget or anything. When it's all working, publish the nuget, switch to Release build config and update to the newest version. The overrides are only used in Debug build config.
Limitations: This won't work well if your package has multiple dlls. It also means that if your consuming project depended directly on any transitively included packages, they would need to be explicitly included in your consuming project directly. Which is probably a good idea in general anyway.