How do I extract the polygon boundary from leaflet? (Either the coordinates or the shape)

Question

I am trying to draw a boundary around points and remove what lies outside of it, but am unsure how to extract the polygon that is drawn using addDrawToolbar() from leaflet. Here are some images of what I have:

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Thanks!

I'm unsure of how to proceed. I see posts on R Shiny but none in the normal console.