  In this work we provide a data analysis of the BOSS galaxy clustering data
with the recently proposed FreePower method, which adopts as parameters the
power spectrum band-powers instead of a specific cosmological parametrization.
It relies on the Alcock-Paczy\'nski effect and redshift-space distortions, and
makes use of one-loop perturbation theory for biased tracers. In this way, we
obtain for the first time constraints on the linear growth rate, on the Hubble
parameter, as well as on various bias functions, that are independent of a
model for the power spectrum shape and thus of both the early and late-time
cosmological modelling. We find at $z_{\rm eff}=0.38$,
$f=0.60^{+0.11}_{-0.09}$, $H/H_0=1.052^{+0.060}_{-0.041}$, and at $z_{\rm
eff}=0.61$, $f=0.69^{+0.14}_{-0.13}$, $H/H_0=1.36\pm0.10$. The low-$z$ $H/H_0$
result is at over 2$\sigma$ tension with Planck 2018 $\Lambda$CDM results. The
precision in these results demonstrates the capabilities of the FreePower
method. We also get constraints on the bias parameters which are in agreement
with constraints from previous BOSS analyses, which serves as a cross-check of
our pipeline.
