I’m using Minwax Pre-Stain Wood Conditioner. I’m trying to find information on whether, after drying, my surface will be safe to prepare food on.
I wouldn't use it. A pre-stain conditioner implies that you'll be following that with a stain of some sort, and then a finish. So to be safe, you'll need to be certain that not only this product, but also the ones that follow it are safe for food contact.
Food prep surfaces take a lot more abuse than do most other indoor woodworking projects. Cutting, scraping, scrubbing, and contact with water, detergents, acids, oils, etc. are all likely to damage any finish you're considering. Furthermore, any film-forming finish you're considering, even if food safe, will be compromised and could end up trapping pathogens. For that reason, wood surfaces meant for food preparation are generally left unfinished or treated only with a food-safe oil, such as food-grade mineral oil.
what if it’s a shelf only meant to hold equipment that comes into contact with food?
A shelf for storing equipment is a very different situation from a surface that comes in direct contact with food. In the case of a shelf, you only need to be concerned about substances transferred to the food by the equipment that was on the shelf. Most sources agree that any commercial finish is "food safe" once it has fully cured, which means that the finish won't transfer to your food just from contact. The idea is that even if the finish contains harmful chemicals, they're locked in the polymerized finish. If those chemicals won't transfer to food, they won't transfer to equipment that will later contact food. Assuming you're going to finish the shelf after the pre-stain conditioner is dry, the finish will form a barrier between the conditioner and the equipment, so the makeup of the conditioner is even less a concern.
From Fine Woodworking: According to the FDA database of approved ingredients for finishes and adhesives, all modern unpigmented finishes (ones that don’t contain lead, mercury or toxic colorants) are technically considered food safe IF they are applied in reasonable amounts and allowed to cure properly.
Bottom line: The pre-finish conditioner is probably fine to use on a shelf or even on surfaces that might come into contact with food or food prep equipment, especially if you cover it with a finish afterward. But I still think it's best to avoid using products like that on surfaces used for cutting, pounding, scrubbing, and other food preparation operations.