Exposing Rust Vec<> to Python via pio3

Question

I'm trying to expose something like this (simplified for clarity) to Python using pyo3:

#[pyclass]
#[derive(Debug)]
pub struct Mesh {
    #[pyo3(get, set)]
    pub vertices : Vec<MeshVertex>,
    #[pyo3(get, set)]
    pub facets : Vec<MeshFacet>,
}

.. such that appending an object to, e.g., vertices in Python would update vertices in the Rust Mesh object. The code above doesn't do that: vertices in the Python Mesh object seem to be a copy of vertices in the Rust object, so updating one won't have any effect on the other.

Relevant code snippets:

Python:

mv = plugin_api.MeshVertex() 
# this updates vertices in the Rust object
mesh.push_vertex(mv)
# this has no effect on vertices in the Rust object
mesh.vertices.append(mv) 

A function to append a vertex to the Rust Mesh object (that does work, but it isn't what I'm looking for):

#[pymethods]
impl Mesh {
    #[new]
    fn new() -> Self { Mesh { facets: Vec::new(), vertices: Vec::new() } }
    fn push_vertex(&mut self, v:MeshVertex) {self.vertices.push(v)}

main.rs:

   let mesh = plugin.getattr("unit_mesh")?.call0()?;

        //now we extract (i.e. mutably borrow) the rust struct from python object
        {
            //this scope will have mutable access to the gadget instance, which will be dropped on
            //scope exit so Python can access it again.
            let mesh_rs: PyRef<'_, plugin_api::Mesh> = mesh.extract()?;
            // we can now modify it as if it was a native rust struct

            //which includes access to rust-only fields that are not visible to python
            println!("mesh vertices {:?}", mesh_rs.vertices);
        }

As you can see, I'm fairly new to both Rust and pyo3. Thank you in advance.