Resources to learn second quantization formalism and how to implement it in code for quantum/computational chemistry research
You could check out any code set that implements configuration interaction wave function methods.  The Journal of Chemical Physics published an open-access article reviewing the state of ab-initio software, and it lists code sets that use CI.
 https://aip.scitation.org/doi/pdf/10.1063/5.0023185
Notably, NWChem uses the second quantization approach and is described in this open resource paper:  https://arxiv.org/pdf/1904.01131.pdf
Finding algorithms to rapidly create valid CI expansions was a big research area in the late 1970's, and the Graphical Unitary Group Approach was created.  There are several open source packages that use the GUGA, including GAMESS. https://www.msg.chem.iastate.edu/gamess/download.html   You can get GAMESS by requesting access and registering.  You could then review the implementation assuming a basic knowledge of FORTRAN.