Last Count, First King

Character-locked: Duke Nuño of Portucale, 1066 (Steam calls him Nuno II Vimaranes) - and per the wiki you must still be playing HIM when Portugal is formed, so this one's a single-lifetime job. He sometimes spawns with the Meritocracy perk for an immediate Claim Throne scheme - check at start. The dependable route: divorce his first wife to free the alliance slot, ally France on day one, declare independence immediately, then use the French to smash the two back-to-back southern wars for Portugal's de jure land. With Fate of Iberia active there's a softer path: while the Struggle sits in its opening phase you can take the Found Portugal route without even being independent.