I don't know anything specific about how the Impossible meatless burger is produced. I know that there are some tricky economics involved in beef production, specifically in government subsidies for the corn which is fed to cattle to make beef; the stream of meat "byproduct" which is turned into "ground beef"; and the huge supply of land and water rights used for grazing cattle which was obtained long ago by huge ranches for free or cheap, which any new at-scale competitor (meat or meatless) will have a hard time beating.
The irony to me is that the $1.55 burger is truly the "impossible" one. Without massive subsidies for feed corn, water, farm labor, etc the value meal burger would not exist.
The meat-free burger will cost customers about one dollar more than the beef version.
https://www.theverge.com/2019/4/1/18290336/burger-king-impos...
Okay so research results:
* A 2 pack of Hot Pockets is $2 and 640kcal.
* Two banquet turkey pot pies are 640kcal for $1.80.
* Cheating somewhat because the ratio is amazing Kroger brand pizza rolls are 1467kcal for $2.77.
* Found a vegetarian option! Totino's Triple Cheese Party Pizza is 700kcal for $1.34.
Hot Pockets are kinda sandwiches I suppose.