We would request to have the feature below, available in the Cloud version of Roadmaps to Jira Server/DC.

Share your project roadmap with offline users, use it in a presentation, or print as a poster for your team's wall by exporting it as an image (PNG format).

To export a roadmap as an image:
Above your roadmap, select Export in the top right corner.

Set the Timeline view, Start date, and End dates, then select Export. The image is automatically download through your browser.

https://support.atlassian.com/jira-software-cloud/docs/share-the-roadmap/