[Semaphor]

> Very few advantages, if any, for most people (only big exception I'm aware of is for citizenship status).

Residency as well, not just citizenship. Other benefits (here in Germany) include: Better adoption rights, no visiting issues when your SO is suddenly in the hospital, tax benefits, and a bunch of other small benefits that you have a decent chance of encountering in your life.

While we mainly got married for her residency, it’s worthwhile to get married for a multitude of reasons. My sister and her husband also decided to get married for the 2nd child, as they also encountered issues being unmarried.