There was a ton of subtext in that scene which is why it's one of my favorite Gus scenes in the series.
There have been hints but no confirmation that Gus is gay and Gus and Max were romantically involved before Hector killed Max.
We see Gus angry. See Gus satisfied with revenge or a job well done. We don't him enjoying himself for the sake of pleasure.
In this scene, we see Gus at a bar he presumably hasn't been to in awhile, at least since being in lockdown once they found out Lalo was alive. We know he's a regular because the waiter, bartender, or more likely the sommelier recognizes him. Gus clearly likes the sommelier and was enthralled by his story about the wine. I don't know if you could say Gus was flirting but he definitely enjoyed himself in a way we haven't see in BCS or BB. His facial expressions said it all. But it also was sad that he could only allow himself the pleasure of the wine and company for a few fleeting moments before going back to his compound and ordering Mike to start back construction on the super lab.