What are the running theories so far?
1. Waiting for Uber Eats order
2. 'Hook up'
3. Checking fishing spots
4. Kidnapping/abduction
5. Something related to the Snap he sent.
My thoughts on these
1. He wasn't waiting for his Uber order. I don't know if you can actively 'track' where the Uber driver is, but if that's possible, then his phone was off (either deliberately or ran out of battery) before it was delivered, making this even less likely. But if he needed to, say, refrigerate the order afterwards, he could have stayed in the apartment and just opened the door after it was delivered. And I'm not trying to imply anything untoward, but simply, to stress my belief that he had gone outside for another reason, and it was not to pick up his food.
2. 'Hook up' is a tossup. I can see it argued that there is no verified evidence of communications. It's more of a "eliminating the other possibilities" than an 'active theory'.
3. Caleb's dad has said on record that Caleb always fished with someone, would not go out alone somewhere.
4. Related to 2, there is also no publicized evidence of an abduction or kidnapping. I think there would be evidence if this happened (shouting, blood, damage to property).
5. People have been going in circles about the snap - whether it a random photo (to maintain streak), if the recipient was important, if it was meant to be a clue of some kind...