Thank you for understanding 🥰 I too have many thoughts on their wedding.
I think Finn and Gray kept it very simple, with only family and a few friends invited. They registered for marriage at the town's municipal office, witnessed by Sayuri and Nathan. Then spent the rest of the day on Windway Bay, where they first met. (As seen on the first page of Chapter 2: Momo and Friends)
Windway Bay is an important landmark in the story, and indeed worth a lot of exploring.