I have a French Bulldog (see icon

) and I transport her in her wire crate when we travel in the car. I think 24x18 is the recommended crate size for Frenchies, and I believe pugs are about the same size as Frenchies, maybe a tiny bit smaller. For the car, this is definitely one of the best ways to go.
Now as far as the LV dog bags, I measured my Frenchie just now (lol) and it looks like she might fit in the LV Dog Bag 50 (which is roughly 20x13.5x9 inches)... not a ton of room to spare though.
I would only bother with something like this if I absolutely HAD to take her on a plane with me, and only because she in particular is a wonderfully lazy dog who curls up and goes to sleep wherever I put her, so I don't think she would be uncomfortable. I would definitely take the dog's personality into consideration for something like this.
There is always the cargo hold for bigger carriers/crates, but I would be cautious, especially with a flat-faced breed like Frenchies and pugs. They are sooo sensitive to heat. Some airlines won't even allow brachycephalic dogs in the cargo hold except in the cool months, even though the cargo hold is supposedly air-conditioned and pressurized. However, in general it is safe... just nerve-wracking for the puppy parents.

(I know of a couple Frenchies traveling in the cargo hold who were just fine.)
I hope this helps!