The laws of Passover refuse the distinction between insider and outsider. Targum Pseudo-Jonathan on Exodus 12:19 says that whoever eats leaven during the seven days will perish from the congregation of Israel, "whether he be a stranger or home-bred in the land."
That parity is remarkable. In the ancient world, religious observance was almost always a marker of ethnic belonging — the gods of the city for the citizens, and other gods for strangers. The Torah here flattens the boundary. If you live in the land of Israel, the law of chametz applies to you. It does not matter where your grandmother was born.
The rabbis read this as an early hint of conversion. The "stranger" here is not any foreigner but the ger — the one who has attached himself to the community. A ger accepts Israel's holidays and Israel's prohibitions on equal terms. A Pesach without leaven is a Pesach without leaven for everyone at the table.
The severity is preserved on both sides. No one gets a lighter version of the law because of their origins. No one gets a harsher version because of their origins. The karet penalty is universal within the community.
This is one of the passages that the rabbis cite to explain why, at the seder, every household is taught to open the door to those who have nowhere to go. The Pesach table is defined by the law it keeps, not by the bloodlines of the people it seats.
Takeaway: Passover makes everyone at the table equally accountable to the same table. Nobody is a tourist on this holiday.