Beta Israel

Needs Royal Court (divergence), no ruler-designer characters: a Jewish ruler in East Africa with a kingdom-plus title creating a divergent culture. The route: King of Abyssinia (any start date), bank piety and convert to Haymanot - restart-scum for Cynical if you want the conversion cheaper - then diverge. Divergence cost scales with realm size, so if your realm has grown, hand vassals to someone outside your de jure land and release them independent to shrink it before paying. Changing Course pops on the same click if you don't have it.