Accessing other plugins

[StrandedSoftwareDeveloper]

Hello, I'm working on my first dnSpy plugin, and I can't figure out how to access dnSpy.Analyzer. Particularly I want to programmatically do the same thing as right-clicking on a method (or class, field, etc.) and clicking "Analyze", and enumerating the "Uses" and "Used By" results. Is there any way to do this?

Also tangentially related question: How do I get an instance of IDecompiler? All the plugins I've looked at look like they just seem to... get it out of no where?

Thanks in advance for enduring my ignorance.
(Also thanks for continuing this project in general, this tool in some ways seems to be better than most IDEs I've used!)