We are moving ideas into "Discovery" status when we do investigations or conceptual work, as well as ideation/design. Basically, anything that needs to be done before the idea can be "Ready for Delivery".
To be honest, I'm not sure we'll continue to do so, because it doesn't give us that much benefit, really. There are certainly other ways to keep track of e.g. design work.
I found it quite interesting to read from Tanguy that the JPD team itsself obviously doesn't use the status field, at all, but "Roadmap" and "Phase", instead: https://community.atlassian.com/t5/Jira-Product-Discovery-questions/What-to-do-when-an-Idea-is-finished/qaq-p/2171378