  We measure the photon-energy spectrum in radiative bottom-meson ($B$) decays
into inclusive final states involving a strange hadron and a photon. We use
SuperKEKB electron-positron collisions corresponding to $189~\mathrm{fb}^{-1}$
of integrated luminosity collected at the $\Upsilon(4S)$ resonance by the Belle
II experiment. The partner $B$ candidates are fully reconstructed using a large
number of hadronic channels. The $B \rightarrow X_s \gamma$ partial branching
fractions are measured as a function of photon energy in the signal $B$ meson
rest frame in eight bins above $1.8~\mathrm{GeV}$. The background-subtracted
signal yield for this photon energy region is $343 \pm 122$ events. Integrated
branching fractions for three photon energy thresholds of $1.8~\mathrm{GeV}$,
$2.0~\mathrm{GeV}$, and $2.1~\mathrm{GeV}$ are also reported, and found to be
in agreement with world averages.
