Expected X-ray luminosity from the combined high- and low-mass binary population in the 2-10keV range versus the measurements . We show the detected galaxies (P_binom ≤3× 10⁻⁴ in the eRASS:4 footprint with blue squares. For non-detections, we plot upper limits using the 99th percentile of the X-ray luminosity (blue arrows). Additionally, we highlight the eRASS:4 luminosities of galaxies with available literature X-ray data (see Sect. 2.4; orange circles). These include data from Seth et al. (2008); She et al. (2017); Baldassare et al. (2022); Ohlson et al. (2023). Some of the galaxies are not detected in the eRASS:4 data but have secure measurements from other instruments available in the literature (orange arrows). A more detailed comparison between the eRASS:4 and literature data is presented in Sect. 3.4.