It's the goose on the left in the pic above? Looks just like my French Toulouse goslings, but could be a different breed because their beaks were turning a bit yellow by this stage.
Happy to hear that it's all working out! I went through a similar thing with panting/stuffy noses and yeah, they're bad at regulating at that age, as they got older it all worked out <3
I know someone that only has a bachelor flock of like 15 or so ganders. Occasionally there are issues, but for the most part, her flock has established its leader and everyone gets along.
The lil one will do totally fine in the car ride home, just bring some water with maple syrup or honey mixed in for them to drink. Ours fell asleep in their tote after about 20 minutes into a 3hr drive. Any kind of gosling around the same age will work out great, and then you can see what sex...
I was in a similar situation when starting out older goslings and younger ducklings. It took a lot of effort for everyone to get along and even now I have a pen built out to separate the geese from the ducks if they get a wild hair.
If you can, get your goose a friend, they'll be happier to...