Nothing is lost in advance but it will be necessary to be more persevering than expected. First of all to put this puppy in confidence in its new environment, let it discover.
Munch, I adopted Maya, a border collie and amstaff cross, as a student, in an apartment, a beginner and quite a homebody. Above all, you need to be well informed, surround yourself and not hesitate to question yourself in order to move forward with your dog. A person in the house having always had dogs who will not seek more to understand, educating his dog will not necessarily be better placed by staying on the achievements of a different dog or unsuitable methods. Thanks to Maya, I learned a lot, evolved and I even became a bit sporty without reaching her level of endurance either. All this does not mean anything, you can evolve at the same time as your puppy, learn from your mistakes, listen to others and to advice (moreover this forum and the members have a lot of very good advice despite some spat).
By taking the puppy’s situation seriously, I personally remain confident for the future.
On the other hand, file a complaint and report the breeder. How could this poor puppy have evolved in such conditions? Even an individual would do better, that’s for sure.
Compensation may be able to help cover the puppy’s vet costs or even find a good educator in your area. The team dog on Facebook will give you good addresses of competent (and above all trained) educators.
Keep us posted, our fingers are crossed for it to develop well.