Use Python extras when installing plugin

[multimeric]

I'm looking into packaging a plugin using "extras", whereby the core package does not depend on Napari, but the plugin does. The plugin will be the same Python package, but with an extra enabled. Unfortunately it doesn't look like Napari has the metadata to tell it "when you install this as a plugin, use the following extra". This makes my solution unfeasible. I wonder if there is a solution to this, perhaps a something I haven't thought of?

Can I, for example, detect that my package is being installed as a plugin during the installation stage?