In addition to having no fans for baseball games at Wrigley Field in 2020, the Cubs had six concerts scheduled last summer that were all cancelled.
Now, those concerts have been rescheduled, per this page on the Cubs website.
Per this Chicago Tribune article, the Cubs will be honoring previously purchased tickets for those six shows, and they are selling tickets online at the link above. Just poking around the ticket links there, it appears tickets are being sold all around the ballpark without restriction, even though the Tribune article states:
It’s unclear how many concertgoers will be allowed at Wrigley Field this summer or if they will be required to take any special precautions to prevent the spread of the virus.