I forgot to emphasize, but- it is important to meet the parents before settling on a breeder or puppy. Particularly with dachshunds, I've seen both the intense/territorial temperaments and the easygoing-boston-terrier-level ones who are just chill with everything. Genetics play a big role in how those turn out.
But if I could make a suggestion, it would be safe to get a puppy from a conformation breeder. Conformation lines for any breed, more often than not, wash out a bit of any intensity in their temperament more or less and would have dogs suitable for what you're looking for... and you could be more sure of the temperament of the dog you are getting.