I have sold the super pretzels for years and heat them by microwave. However I am now selling their "cousin" which is made by the same company but they are stuffed with sweet cream cheese, jalapenos and mozerella cheese, and pizza sauce and cheese. I find the outside to be okay visually but the inside stuffing does not turn out as nice when done the same way. It is more rubbery. What/how can you heat these so they turn out like they have been in an oven but can be done quickly. I am in a concession trailer so space, power and time are all critical.
In case you do not have specific instructions from the company making them or a special warmer (see comments), I would try microwaving them first (e.g. defrost) and then broiling/baking them.
Alternatively, I've seen fast food cooks blast frozen foods in the microwave at high for a little while before throwing them into the deep-fryer, maybe that could be an option as well.
Or, since you mentioned that space/power/time is of the essence, you might even be able to use a combined microwaving/broiling function in case your oven offers it.
Experiment a little and you should be able to get the settings right quite fast.
PS: I'm assuming that thawing a few products beforehand is undesired and therefore leaving out that possible option.