I conjecture non-zero bare masses for nearly standard-model photons or gluons, derived from quantum-mechanical localization at a cosmological scale. That entails the existence of photon or gluon Bose–Einstein (BE) condensates in a comoving Friedmann–Lemaitre–Robertson–Walker geometry. I derive tantalizing results that set the inter-particle distance in these BE condensates almost at the nucleon scale and a corresponding critical temperature of condensation almost at the end of the quark epoch or the beginning of quark–gluon confinement. My estimates for particle mass and number density in these BE condensates suggest remarkable relations among fundamental constants, h, c, G, Lambda , at the most microscopic and cosmological scales of quantum and relativity theories.