How can I migrate and merge a set of projects into a single project on a new server?

We have a set of Jira projects on a server, which we need to change to a new server. At the same time, we want to merge those projects into a single project.

How can this be done, conserving workflows, columns, permissions, filters, components, etc.?

I see how to migrate a complete server, one by one, but I do not see a way to merge and migrate selected project instances. In addition, the destination server already hosts many other projects, which we do not want to eliminate.