Without trying to sound like MegaDolly I don’t think it’s unachievable for him to fill a standard sized arena for a one night gig :D A few decent TV bookings over the next few months should probably help shift some tickets. It’s not like he’s trying to fill Wembley Stadium :D
https://www.bbc.co.uk/news/live/c9wpq8xrvd9t
My relatives in Portugal don’t have any, they’re saying it’s out in parts of Belgium, France and Germany as well :o