If the dog spoke English, I'd play in that game.

There's also nothing saying the dog is going to be any good at it, but I've seen a few humans do worse than I'd expect from a Chihuahua so I guess it would be better than nothing.

Who says you have to have an AL adventure? I've played in stores a ton but never used one that I recall. Nothing against them, some of them are pretty decent adventures, and they'd be a fine choice, but they'd only be necessary if someone insists that you use one.

and for those who wish to play pathfinder, 2e.aonprd.com/ has every rule completely for free

edit: forgot to say there is also nothing that says you can't be a GM if you're a cat or a dog