You might be able to sit on the steps of the 2 pillars at the front of the pavilion, but odds are good that people will end up standing in front of you blocking your view
Same deal for the tables there on the right.
Sergio performs essentially where the patterned ground is in front of the large tower.
Thank you for providing the perfect picture to explain the situation! I’ve seen Sergio a couple of times, and didn’t remember much for seating around that area. Plus, as you said, there will be plenty of people standing all around his area, blocking much of the view from any seated position.
This doesn’t surprise me too much. World Showcase used to open later than it does now (before Remy and FEA were a thing) so a phased morning opening makes sense. They expect most people start their day in the area fka Future World.