I think the problem with both of your arguments is that neither of you will be able to actually define consciousness in a way that is satisfactory to the other

I think the problem with both of your arguments is that neither of you will be able to actually define consciousness in a way that is satisfactory to the other party. Which is cool. Because we don't really fundamentally understand what it actually is. We have a rough feeling, but any definition we put forth will either also be satisfied by something you both agree is not conscious or not be satisfied by something you both agree is conscious. So we can't really say if it is emergent or fundamental. And it may even be a property of purely mechanical elements.