  We report on first measurements of branching fractions~($\mathcal{B}$) and
CP-violating charge asymmetries~($\mathcal{A}$) in charmless $B$ decays at
Belle~II. We use a sample of electron-positron collisions collected in 2019 and
2020 at the $\Upsilon(4S)$ resonance and corresponding to $34.6$\,fb$^{-1}$ of
integrated luminosity. We use simulation to determine optimized event
selections. The $\Delta E$ distributions of the resulting samples, restricted
in $M_{\rm bc}$, are fit to determine signal yields. Signal yields are
corrected for efficiencies determined from simulation and control data samples
to obtain branching fractions and CP-violating asymmetries for flavour-specific
channels. These are the first measurements in charmless decays reported by
Belle~II. Results are compatible with known determinations and show detector
performance comparable with the best Belle results offering a reliable basis to
assess projections for future reach.
