Of course! Passover is fun. And it’s meant as a time to reflect on freedom and stand in solidarity with anyone who is unfree. Non-Jews are typically welcome at Seders as well.
(Some Orthodox Jews who hold traditional readings of Exodus could theoretically take issue with Gentiles observing Passover — Exodus 12 says that uncircumcised males are barred from participating in the sacrifice of the Passover lamb. But that sacrifice isn’t part of the holiday for Jews anymore, and the restrictionist attitude is far from common among US Jews.)
Seders are supposed to be accessible. That’s one reason they’re held at home rather than formally in a synagogue. The format invites the hosts to personalize the ritual a bit. Some families can get quite creative.