A compass doesn’t ‘point north’, that’s a lie to children, it’s inside a large magnetic field.
You’re going to have issues as you get near the Earth’s poles, but merely changing hemispheres won’t make a fig of difference. Your antipode friend was “coming the raw prawn” I believe.
You’ve contradicted yourself nicely there.
Think about how the compas ‘sees’ the magnetic field, near the equator the field is almost parralel to the earths surface, near the poles the firld is near perpendicular. You can buy compases that have the magnet aligned so that it works best at a certain latitude.
If you buy an electronic compas it wil need calibrating if you move more than a hundred miles or so, usualy by placing it on a level surface and rotating it 360deg a number of times untill it’s worked out what angle the magnetic field is at.