Who said th ex interviewee must present 'own' code there?
The conversation can just as well be around a library, product or system that isn't authored or contributed to, by the interviewee.
'What architecture is used here, and what are the down and upsides in this implementation'. 'What would you do different'. 'Which part do you admire, and what don't you like'. Etc.
Also why would I voluntarily talk about codebases authored by anyone other than me while having in-depth knowledge about it? Nobody looks under the hood of things that interests them, let alone be critical of it’s design.
Talking about product and system design is something that is vastly different than stand-alone codebase. If you as an interviewer are interested about something you have the capacity of directing the conversation flow toward that. Ask them introductory questions about a product/system, gauge their interest in it then ask their opinion about it.
> Nobody looks under the hood of things that interests them, let alone be critical of it’s design.
Do you honestly believe this?
Many people do this. I do this. It's the best way to learn¹. There are repeating Ask-HN threads requesting for "high quality Open Source Software to learn from" for example.
¹Edit: on second thought: probably not the "best" way. Not for me, anyway. Just a good way.
The conversation can just as well be around a library, product or system that isn't authored or contributed to, by the interviewee.
'What architecture is used here, and what are the down and upsides in this implementation'. 'What would you do different'. 'Which part do you admire, and what don't you like'. Etc.