How to set uniform atmospheric pressure (and uniform pressure from within)?

variational formulation
1

So say we have a unit sized hollow sphere. It has an inner radius r and outer radius R and when meshed looks like this:

image
image1884×1018 104 KB
(image source: https://comphysblog.wordpress.com/2018/08/26/3d-electrostatics-using-fenics/)

I want to see how such mesh being created from some material
M would react to uniform atmospheric pressure from outside P and uniform inner pressure p from within. The main idea for me is to deform shell in future yet keep uniform pressure on its surfaces.

How one can set conditions for uniform inner/outer pressure in FEniCS?