k_bol, X vs. α_ox for the high-λ_Edd AGN in our sample (blue triangles) compared to the XMM-COSMOS type-1 AGN (light grey crosses) of Lusso et al. (2010). The solid black line refers to their best-fit relation, with the dashed black lines describing its 1σ spread. Green squares and red circles indicate the sub- and super-Eddington AGN from Liu et al. (2021), respectively. Purple diamonds are the hyper-luminous WISSH QSOs from Zappacosta et al. (2020).