  Kaonic atoms are a unique tool to explore quantum chromodynamics in the
strangeness sector at low energy, with implications reaching neutron stars and
dark matter. Precision X-ray spectroscopy can fully unlock the at-threshold
isospin dependent antikaon-nucleon scattering lengths, via the atomic
transitions to the fundamental level. While the SIDDHARTA experiment at the
INFN-LNF DA$\Phi$NE collider successfully measured kaonic hydrogen, its
successor SIDDHARTA-2 is starting now its data taking campaign aiming to
finally fully disentangle the isoscalar and isovector scattering lengths via
the measurement of kaonic deuterium. An overview of the first experimental
results from a preparatory run for the SIDDAHARTA-2 experiment is presented.
