  We compare the ground-state features of alternating ferrimagnetic chains
$(1/2, S)$ with $S=1,3/2,2,5/2$ in a magnetic field and the corresponding
Holstein-Primakoff bosonic models up to order $\sqrt{s/S}$, with $s=1/2$,
considering the fully polarized magnetization as the boson vacuum. {The
single-particle Hamiltonian is a Rice-Mele model with uniform hopping and
modified boundaries, while the interactions have a correlated
(density-dependent) hopping term and magnon-magnon repulsion.} The
magnon-magnon repulsion increases the many-magnon energy and the
density-dependent hopping decreases the kinetic energy. We use density matrix
renormalization group calculations to investigate the effects of these two
interaction terms in the bosonic model{, and display the quantitative agreement
between the results from the spin model and the full bosonic approximation. In
particular, we verify the good accordance in the behavior of the edge states,
associated with the ferrimagnetic plateau, from the spin and from the bosonic
models. Furthermore, we show that the boundary magnon density strongly depends
on the interactions and particle statistics.
