  We present progress towards a unified framework enabling the simultaneous
determination of the parton distribution functions (PDFs) of the proton,
deuteron, and nuclei up to lead $(^{208}\rm{Pb})$. Our approach is based on the
integration of the fitting framework underlying the nNNPDF3.0 determination of
nuclear PDFs into that adopted for the NNPDF4.0 global analysis of proton PDFs.
Our work paves the way toward a full integrated global analysis of
non-perturbative QCD -- a key ingredient for the exploitation of the scientific
potential of present and future nuclear and particle physics facilities such as
the Electron-Ion Collider (EIC).
