  A symmetry-preserving regularisation of a vector$\times$vector contact
interaction (SCI) is used to deliver a unified treatment of semileptonic
transitions involving $\pi$, $K$, $D_{(s)}$, $B_{(s,c)}$ initial states. The
framework is characterised by algebraic simplicity, few parameters, and the
ability to simultaneously treat systems from Nambu-Goldstone modes to
heavy+heavy mesons. Although the SCI form factors are typically somewhat stiff,
the results are comparable with experiment and rigorous theory results. Hence,
predictions for the five unmeasured $B_{s,c}$ branching fractions should be a
reasonable guide. The analysis provides insights into the effects of Higgs
boson couplings via current-quark masses on the transition form factors; and
results on $B_{(s)}\to D_{(s)}$ transitions yield a prediction for the
Isgur-Wise function in fair agreement with contemporary data.

High Energy Physics - Phenomenology;High Energy Physics - Experiment;High Energy Physics - Lattice;Nuclear Experiment;Nuclear Theory