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: Vienna-Simcoe SMaSH
Secondary: RIS (bulk aging)
Bottled: Deception Cream Stout, 米酒 (rice wine), Wedding Pale Ale, JAOM, Four-Quarters IIRA, Wedding Wheat
Coming Up: Tea Beer - Round 2, The Lukewarm, The Pious