Baker's malt extract is different from brewer's malt extract. I think you can use the brewing stuff for baking, but not the baking stuff for brewing. That said, I suspect a light malt extract would make a basic, classic pretzel, while you would get darker pretzels and more complex and roasty flavors from darker malt extracts. Approach the pretzels like a beer recipe and you should be able to control your output in a similar way.
Primary: Orange Peel JAOM, Orange Rind JAOM, Pomelo Rind JAOM, 11g APA
Secondary: RIS (bulk aging)
Bottled: Pu-er Pale Ale, IIPA, Deception Cream Stout, 米酒 (rice wine)
Coming Up: Four Quarters IIPA (25-Cent, 15-Minute, 90-Degree, and Three-Month), 11g Wedding Wheat
Other: Chinese-Style Pickled Radish and Carrots