If you are going into the next pup with service dog in mind talking with a service dog training facility may help you evaluate your new pup faster and let you know if your dog has service dog potential.
I have a service dog. The statistics for dogs that "fail" (doesn't mean they are not perfectly lovely pets) is higher than most think.
If you start out with a service dog training group they can help you pick your pup and train. They will also help you assess you training experience.
Lots and lots of service dogs are rescue
. But temperament, background, and intelligence are important. Folks who train them are great at selecting the ones that will be successful and which ones will be pets. They can tell you the age they do the selecting and what age to start training. Some pups are smart, loving and delightful to be around but just can't over come distraction or some levels of fear - my friend has a pet that could not make it through service dog training who is our absolutely favorite play date friend
Good luck with your new pup when you are ready to go there! It will be an interesting trip!