Yes you are correct that there is no win condition, and the only way to lose is from the heat. We wanted to add another lose condition where if you failed to fill a certain amount of orders then your boss would fire you. It's also maybe a good idea to have the rabbits/snails remain at the farm patch until you shoot them, instead of them leaving after they eat a plant.
Great idea on expanding the shop! Some sort of auto defense, or auto planter/harvester could be great additions, and could really turn this game into a decent "idle" game potentially.
Thank you for playing and leaving feedback!