Oran doesn’t stand on ceremony really. From what he’s thought about, he prefers a smaller ceremony, maybe an outdoor wedding. Friends and family would make up the guest list, keeping it maybe a bit small, and then afterwards, a big party, lots of food, people having a good time, maybe a couple of playlists so people could dance. And halfway though, he’ll pull his spouse away and they’ll celebrated in bed, away from the crowd.
As for marriage itself, it’s a commitment that he plans on making for life, which is partly why he hasn’t married yet, despite being closer to middle age then young adult. He doesn’t have any real concepts for it beyond that, that he’ll spend the rest of his life with someone he loves. Why put rules on that? (beyond insisting on monogamy. I can’t see Oran really doing polyships.)