A few important factors influence what your galley is able to produce. Ships are able to utilize techniques and equipment developed in the revival of urban restaurants over the past two decades.
These urban spaces were often small and repurposed from some other business that had nothing do with food. Just because they were small doesn't mean they were inexpensive. A forty by ten foot kitchen could hold a million dollars or more of equipment, plus eight cooks.
You don't need to spend a million dollars or even have a proper galley to enjoy good food if you plan ahead.
Microwave - The beloved cooking device of sailors everywhere. One of the least expensive items on this list, great return for the money invested, and uses little power because of short cook times. Also easy to secure to a surface which needs to be done with all appliances on board a vessel.
Electric Flat Top and Grill - This does a good job of cooking things that do not do well in a microwave, like hamburgers. Power intensive for the smallest vessels when other appliances are added to the load.
Larger vessel might have something closer to the restaurant kitchen example.
Tilt Skillets - Just like a big frying pan except things slide out when you tip the large boxy cooking surface with a handle. Good for sauces and stews.
Steam Kettle - This is kind of like a double boiler but it's a large kettle on a frame which allows it to pour out the contents. Steam is circulated in between the double walled kettle for even heating. Great for soups and pasta while being safer than an open water bath. A steam kettle will also produce higher temperatures than a water bath because of the pressurized steam.
Ovens - Supported with gimbals on smaller vessels to keep them even so they don't develop hot spots. An oven is often the one item that allows a kitchen to produce comforting food for the crew. Package bread is fine, but fresh bread is far better. Frozen loaves and rolls take minimal prep time and store well long term. That topic is discussed more in Building a Ship's Pantry if you are interested.
Steam Ovens - Both a steamer and a regular oven which is very popular for small spaces. Good for slow cooking at lower temperatures.
Stoves and Broilers - Very similar to restaurant models but with some extra framing to bolt to the floor and bulkhead. It would seem kind of dangerous but a good cook knows the galley and when it is safe to cook. Small vessels can use electric burners if they are at least as large as the bottom of the largest cooking pot. Small gas units are also available.
Gas Grill - This is getting luxurious, where is the lobster tank? These installations require serious air exchange systems and big gas supply lines.
Warmers - Sailors eat at all times of day so these thermal boxes are must haves for latecomers or off time meals.
Box Cooler and Freezer - You can't eat what you can't store. What you lose in efficiency by installing an over sized unit you gain in crew moral when frozen fresh summer fruits appear on the table on a grey wintery day. Even small boats can have a refrigerator for shore prepared lunches. Once again bolt and strap all of this down, you don't want a loose appliance.
Dry Pantry (Dry Box) - This is where you keep non-refrigerated items. Bulk packaging needs to be secured so it doesn't shift so storage places have nets or straps to hold items in place. Retainers are also useful in coolers but less common for some reason.
A dry pantry needs to have stock rotated and organized. Most galleys inventory supplies each week to anticipate need.
Skill - This isn't equipment but it is essential. The galley is a complex operation and if it fails you will have an unhappy crew. Luckily all of the skills needed are found in land based restaurant kitchens and most cooks adapt well. Food service can also be a way onto a ship for the interested but inexperienced mariner.