One of the challenges for product managers is to maintain an up to date product roadmap. If the roadmap is public, then that becomes a bit more difficult with customer scrutiny coming into play. Most of the Roadmap softwares fail at the point when they need too much manual intervention just to stay up to date.
Roadmap portal for Jira Service Desk addresses this problem in a smart way. Life of the product manager becomes a tad bit easy since Roadmap cards can be auto-updated based on software development status in Jira. One doesn't need Zapier or any other such tool to achieve this. Default JSD automation feature is sufficient.
Custom Field or Status?
At the end of the day the roadmap portal shows cards based on Jira issues. As explained here, each column retrieves issues based on configured JQL query. Now if you are aware of how JQL works, you would know that one can retrieve issues based on one or more of their attributes (default as well as custom ones).