Radio luminosity function estimation of quasars (blue) based on the UV luminosity function of Matsuoka et al. (2018b) at z = 6 and rescaled radio luminosity distributions of Macfarlane et al. (2021). The RLF in blue is obtained using a M₁₄₅₀ cut of −22, corresponding to future deep optical surveys like Euclid at z = 6. The M₁₄₅₀ limit of the Legacy and SDSS survey at z = 6 are −24.1 (dotted line) and −25.9 (dashed line), respectively. The z = 6 RLF is compared to the model of Saxena et al. (2017) in green for a population of radio galaxies at z = 6 and to the evolving radio-excess AGN pure density RLF fit from Smolčić et al. (2017) extrapolated to z = 6 in orange. Since we extrapolate the fit of Smolčić et al. (2017) to higher redshift and luminosities, the bright end (≳10^26.5 W Hz⁻¹) is not well constrained.