You are allowed to remain in the country for up to 60 days after your employment...

paxys on Jan 26, 2024 | parent | context | favorite | on: How I got an O-1 visa as a software engineer

You are allowed to remain in the country for up to 60 days after your employment ends. The author doesn't mention how long they stayed, but it is possible that the "exploratory work" was done within that period.