I don't think it's open carry but if it's not in my pocket I like a OWB holster (usually with a thumb snap) under a long shirt or jacket/vest.
I'd call that concealed. The gun's covered, unless it's short enough to ride up if you reach for a tall shelf or something, I guess. When I think of open carry, I think of the jackasses in my area that stop just short of kicking the door in screaming, "I have a gun!"
The P365 is nice to shoot for it's size in 9mm and is awesome to shoot in .380
Had a bit of an odyssey with a woman recently trying to find her a carry gun. I'm not, like, some super operator or anything, but I have been pulling triggers for the better part of thirty years, so I at least know enough to not just hand her a .38 Airweight and call it good. She learned on my P95, which she shoots pretty well. Better than I do, if I'm having a bad day when she's having a good one. Her one complaint is that it's too big for her hands, so we went to a range, paid far, far too much money renting basically everything they had Glock 19 sized and smaller. She landed on a P365 XMACRO, or however they stylize it, after shooting basically every variant of the P365 and Hellcat lines. I also ran about half a mag through each, just out of curiosity. I do find both the P365 and the Hellcat deceptively well-behaved for how small they are, but the jump in comfort from the base P365 to the Chungus Edition™, and from the base Hellcat to whatever the fuck Springfield calls the bigger one of those, is absolutely worth the extra mass.
As an aside, she hated every variant of the Hellcat she touched. She described the ergonomics as like "trying to shoot a fucking Snickers bar."