  Due to universality and attractor properties, $\alpha$-attractor
quintessential inflation establishes direct relations between inflationary
observables such as the scalar tilt $n_s$ and the tensor-to-scalar ratio $r$,
and late-time dark energy equation of state parameters $w_0$ and $w_a$. In this
work, we examine three different physically motivated regimes, considering
complete freedom in the parameter $\alpha$, models inspired by supergravity
where $\alpha$ takes on values up to $\alpha=7/3$, and Starobinsky inflation
($\alpha=1$). We investigate the consistency and constraints imposed by Cosmic
Microwave Background measurements from the Planck satellite, B-mode
polarization data from the BICEP/Keck collaboration, and low-redshift
observations. Additionally, we consider small-scale CMB measurements released
by the Atacama Cosmology Telescope, which give results approaching the
Harrison-Zel'dovich spectrum ($n_s \approx 1$). Here $\alpha$-attractors lead
to an improved fit over $\Lambda$CDM. For the large-scale CMB measurements,
$\alpha\gtrsim2$ models can provide equally good fits as $\Lambda$CDM.
