I think when most people hear "wedding night" they think of something steamy. However, this 10 minute special is definitely not steamy (and I'm annoyed that they cut away from the kiss at the end). It shows Maki & Haruta talking about chores, finances, doing a house tour and generally being sweet. It also does not take place after their wedding ceremony but during episode 1 so I would suggest watching it after you've watched episode 1. Aired on GagaOOLala.
https://www.gagaoolala.com/en/videos/4081/ossans-love-returns-tver-spin-off-2024