I want to refer to this KB article on Boards in the new JIRA experience which has the following statement in it:

Previously, there were global boards that contained work from multiple projects. Those are a thing of the past.

Since boards now have their own location, the sidebar displays options relating to the project that contains the board. Even if your board contains issues from several projects, the sidebar remains project-centric, giving you quick, navigation to the work related to your project and board.

This is not how we use JIRA Software. And many of our customers don't either. Many of our customers support multiple external organisations and have set up JIRA Projects per customer. Other companies have multiple Jira projects per application they support, but share teams and other resources across, so they need a common view on this backlog.

Our own consultancy team has a shared board to manage the backlog of 50+ projects. How could we possible associate this with "a project"? Or with a user profile?

Our key boards are not project centric at all, but team centric. And these key boards are our primary place to go to in Jira.

So, global team boards should be prominent, easy to find and definitely not 'a thing from the past'