Using an electric field to rip apart a nucleus

Due to Newton's shell theorem, the electric field in any uniformly charged shell is zero. Disregarding that, lets say there is some external field where the nucleus is. Such a field would likely be uniform on such a small scale. Since the external field is being applied by an external force, the external field has no divergence where the charge is. That means that if you had a closed surface there, like a sphere, there'd be no net electric flux going through it. As such, the electric field won't be able to rip the nucleus apart, the best it can do is distort it.

It appears quite impossible to induce fission with an electrostatic field, but gamma rays can actually induce fission in fissionable elements. The reaction known as photofission. See for example https://en.m.wikipedia.org/wiki/Photofission.

The concepts have to be clear. Nuclei belong to the quantum mechanical regime, as you yourself acknowledge with :

to overcome the pion exchange between the protons and the neutron and the protons.

In the quantum regime there is no meaning to "ripping apart" if not expressed as particle exchanges , analogous to the pion exchange rough model for the binding of the nucleus. The energies needed for this have to be larger than the binding energies , i.e. order of MeV. Thus the particle exchanged in order to "rip" the nucleus has to have order of MeV energy.

As you are talking of electric fields , the QM particle that exchanges electromagnetic forces is the photon. If you look at the table you will see that this is in the range of gamma rays.

The interaction of an electric field with solid matter, is through the exchange of photons, in this case gamma rays. This is not an energy range that can be reached to build up electric fields using solid state matter. So as the answer of my2cts says gamma rays can split up a nucleus.