>>56045895There are bigger bird mons to choose from than Squawkabilly, for sure, but none of them are anywhere close to being as big as Corviknight. Unless you count the titan Bombirdier... but at that point, you could probably just ride in its pouch, instead of needing the taxi car.
I think Alola had it right using Charizard as a ride 'mon. Riding on the back of something decently-sized, like a dragon, just seems a lot less likely to go awry. I don't know why they don't just strap a saddle on Corviknight in Galar, it's big enough to do that easily, and riding on a bird like that seems way more fun.