I asked a friend in Taiwan for her opinion, and just made everything more complicated: 喝粥，吃稀饭, she said. Even though most places say 粥 and 稀饭 are the same thing... (they even have the same emoji lol 🥣🥣). She said: "粥应该比较像很浓的米汤，所以喝的。稀饭比较像是煮得很软很软的饭，所以我们说吃稀饭," and added “不过粥和稀饭，用吃或食用喝的，都应该没关系," so I give up. If you chew it it's 吃 and if not it's 喝, apparently? *facepalm*