I don’t think getting a pet dog or cat is in any way comparable to adding another human on this planet. Sure they do eat food, but generally nowhere near as much as a human. They also don’t drive cars, shop fast fashion from China, fly away on foreign holidays or travel on a cruise ship.
I have two dogs and what they own is a collar and lead each, a bed each, a few tennis balls and some rope toys. I also have two kids, and although I do try and be sensible when it comes to buying stuff, they have many thousands percent more stuff than my dogs.
My dogs also gets around using zero emissions (walking), my kids use busses, trains and uber (teenagers).
However, if you do want to blame the animals, then have a look at the meat industry, particularly beef.