There’s been a lot of debate over whether aquatic creatures could develop sapience without fire, but I saw a post pointing out that bags to carry things in was just as important a human invention as fire was, so if dolphins or cephalopods developed the ability to carry supplies in bags, would that make up for the lack of fire?

I don't think there's an issue with aquatic creatures being sapient, but with them developing advanced technology; without fire you have no clay, glass, or metals other than cold-worked copper/silver/gold, and a viscous turbulent medium is going to interfere with grinding material and building complex machinery, not to mention electrical circuits. In A Matter of Time I have far-future marine…