This is a very interesting question, the importance of making the purchase in person varies a lot according to what will be your intention with the dog or the importance you will give to the animal's temperament. As for the interaction with the animal, it is more about what you will do with the dog. For example, an animal that will be used for sports such as agility, or work as grazing, it is best to have tests done for a greater guarantee of performance and these tests must be done in person or by someone you trust in order to obtain a reliable answer. .
As for the animal's temperament, it is important to know if the animal is more agitated, noisier or more peaceful, according to your preference. A trainer, a trainer or a professional in animal behavior can be a good option of help at the time of purchase.
Hope this helps