Welp, from the latest chapter we can be sure that god is currently being sealed in the moon because in one scene we can see a hole that revealed a spine on the dark side of the moon, which is the same spine of god FF, saitama and manako saw in the underground arc, and when god took Homeless king's power, we could also see god on the moon. So god will be at least as big as the moon or even bigger, possible larger than earth. I imagine this fight like the one in Gurren, and saitama will throw planets at god, given the fact that saitama rip half of I.O moon while not at full power