We discuss exclusive heavy vector-meson production using two approaches that mitigate the notoriously large scale dependence of the collinear factorisation results at Next-to-Leading Order (NLO) in $\alpha_s$. We perform a parton analysis using one of these approaches within the PDF fitting tool {\sc xFitter} to determine the gluon PDF at moderate-to-low values of $x$ based on ultraperipheral collision (UPC) measurements from the LHC. We emphasise that a combined fit to exclusive heavy-quarkonium production data from multiple collision systems will not only deepen our understanding of the underlying theoretical mechanisms at play in UPCs, but also significantly improve our knowledge of the gluon distribution in protons and heavy nuclei at small $x$.