Webster definition of Lodestar: 1 archaic : a star that leads or guides especially : north star. 2 : one that serves as an inspiration, model, or guide.
I love how Oda basically uses both definitions in a way since the island gave Roger the INSPIRATION to look for Laugh Tale and want to be Pirate king and it's literally the island that LEADS to Laugh Tale
Anyway, it being the North star is extremely fitting since the North start was the primary navigation method for Sailors way back when before GPS and maps.