I was given this as an interview question once, it was fun. I was told to go into “as much breadth and depth as possible” but I did get stopped a couple times when I started talking about things like debouncing.
To clarify, I would ask this question as a wrap up, a sort of final probe of depth test. If they don't go into much detail, no big deal. If they were good in the rest of the interview, they'd still get hired. If they were good elsewhere but also went into depth on this question, then it really boosts their likeliness of getting hired. I find that people who are curious about how things work, especially when it is outside of their main domain, are usually people interesting to work with.
If you want a thoroughly obsolete look at debouncing, I got a debouncing module from an IBM 705 computer (1954). This module was built from 8 vacuum tubes and a pile of resistors and other components. I powered it up with an inconvenient set of voltages (+140V, -60V, -130V) and actually got it to work: http://www.righto.com/2018/01/ibm-mainframe-tube-module-part...