I am a Glock fanboy to the core, my daily carry is a G19 and I compete with a G17 & G45.
I owned a G43 for about a year and added Tango Down +2 extended magazine bases to the mags I carried for reloads and carried the stock 6 round mag in the gun, it had Ameriglo CAP night sights, a Talon rubber grip wrap was on the gun, it had a Ghost connector and an IDP trigger shoe installed and the gun shot like a laser beam, it vanished while in an IWB holster and I had zero issues with pocket carry as well, but at the end of the day I only carried the gun maybe 2 times a month so I sold it.
My wife and daughter both carry the Shield 9mm and they as do I, love the gun. The Shield 9mm handles recoil like compact gun and all of us shoot then well, even with +P ammo, for IWB they melt away and are absurdly easy to carry, but for pocket carry I find the Shield to be a smidge too big when wearing jeans, it is doable if you’re wearing pants with larger pockets, cargo shorts is a non issue, but hell I can carry a G17 in my cargo shorts pocket lol.
I do not own a P365 but I have handled and shot one, in my opinion it “should” pocket carry exactly as well as the G43 and better than the Shield because it is just a bit smaller in all of the correct places to edge out the Shield for pocket carry.
If I were buying one of the three guns mentioned today for pocket carry it would be a P365 hands down, I think the Shield 9mm shoots the best out of the three guns and of the three I could shoot the Shield all day without any discomfort, the P356 is nearly as shootable with the G43 being just snappy enough to cause fatigue faster than the three.
With all of this said, all three of the guns I listed will all do the job extremely well but they each have a niche that they fill better than the others, so if pocket carry is your biggest concern I’d look to the P365 and the G43, again even though I’m a huge Fan of all things Glock I believe the P365 is a slightly better gun.