Cook anything in hotel room with our pressure cooker and/or with our induction stove.
Standard at pretty much every hotel around the world. Fire hazard.
Don't allow their restaurant' kitchen for this 5 minute cooking thing.
Standard at pretty much every restaurant around the world. Health, safety, fire etc. Are you familiar with a commercial gas stove? Probably not.
Won't give us facility to just cook the food in their kitchen and give it back to us.
Most busy kitchens don't have the time, and most short-order cooks aren't interested in the liability of preparing unfamiliar (to them) meals for an infant with declared health issues.
Your two best choices are:
Hotels with kitchenettes, also called apartment hotels, wherein you will find a standard domestic kitchen. Like AirB&B.
Full-service hotels that are quite used to odd requests from guests. Some place that advertises 24-hour room service and 5-course formal dining. They will be happy to accommodate your dietary request because you will be paying a fortune for the room. Still highly unlikely they will cook your food though. They will cook your recipe, just not your ingredients.
One option you may not have considered is boil-in-bag meals. Something in a sealed bag that just needs 3 minutes in boiling water to prepare. This eliminates almost all of the objections the kitchen will have as they do not have to handle the food in any way. It needs to look commercial though - expect rejection (and food poisoning) if you prepare it yourself and use a Ziploc freezer bag.