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.
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