Neither French Bulldogs nor Pugs are actually low energy breeds. Some are, especially as they get past around 4 or 5, but a great many members of both those breeds do tend to be energizer bunnies that don't stop moving.
That said, they are both small breeds that can usually be exercised efficiently in the house by playing a game of fetch, or tug, or just letting them run around. They do tend to be busy little dogs that always want to play, though, so while they aren't too difficult to exercise, they are not low energy.
Also, both tend to be prone to some pretty knarly health issues. Even the "well bred" members of both breeds will have trouble breathing during/after heavy exercise, have trouble in the heat (as in, over 70* and sunny, an in high humidity are in real danger at 70*+ and sunny), and trouble in cold weather (as in, below freezing). Bulldogs are prone to issues with elongated pallates, and Frenchies have some predisposition to allergies as well. Both, but especially Pugs and the very bug eyes Frenchies, are prone to eye injury and will have trouble in sandy places (often sand gets in their eyes and causes abrasions that then require vet care).
Could you maybe describe what you mean by "don't require a lot of exercise"? Do you mean don't need to be taken for hour long walks twice a day, but are OK with 2 or 3 20min walks a day? Won't ever leave the couch because they just want to sleep? Are maybe not super lazy but can be exercised efficiently inside and just go outside for going to the bathroom/for the odd long walk? Do you live in a place where it gets very hot or very cold? How playful a dog do you want? How many walks are you able to give a dog and for how long?