I find almonds are good, not the candy-coated ones, those are too high carb. Do you carb count? Junk food’s not the best but a few chips, which you can assess with carbs and Cals, and bolus for, with a bit of cheese and cucumber, and a peanut butter sandwich, which you can carb count from the jar and the bread wrapping, might fill you up. As long as you like those things. You could keep it all to hand for the next junk food feast.
By the way, carbs and Cals, which you can get as an app, also covers burgers, fish and chips and quite a few other takeaways. If you know your ratios then it’ll make life easier, though because junk food often has a high sugar and fat content it’s not something I like eating myself; it can cause a spike and sometimes also takes a long time to be digested. That’s not to say that I totally forego fish and chips, especially the crumbed fish and sweet potato chips!