I think it's easier to mention the restaurants that probably are harder to fit into keto. In my experience, Italian, Mexican, and Asian head that list.
A lot of Italian places load up on the pasta. It's hard to avoid an entree that does not come with pasta or (sometimes) beans or rice. Tomatoes and onions can provide a surprising number of carbs, too, especially once the water has been cooked out of them for sauce. My best bets here usually are salads (hold the croutons, dressing on the side), simply prepared seafood (not always easy to find and not always the best bet at less-than-the-best restaurants), and braciole, which is essentially a meat rollup. Pizza tops can be an option if you stick with non-sugary toppings (avoid choices like BBQ beef or pineapple).
Mexican can be okay but imo there are a lot of landmines. Tortillas, beans, and rice are the obvious items to avoid by themselves, but sometimes they're mixed into the dish in such a way that they can't be removed (by you or the kitchen). Taco meat often comes with seasoning that has a surprising amount of sugar or fillers in it. Many sauces are thickened with masa (corn starch). This leaves even safe-looking choices like the taco salad (sans tortilla bowl) higher in carbs than you might think. Fajitas usually are a safe choice here if you forgo the tortillas. But that's not a very wide selection.
Asian can be good if you can avoid the dishes with potatoes and noodles and keep the rice on the side (or, better, in the kitchen). Many sauces, however, are thickened with starches (tapioca, potato, rice, etc. that are highly refined) and they're impossible to separate from the protein and vegetables that otherwise would fit into keto eating. And a lot of fried food is battered with a floury coating. Many cuisines (particulary in the US) will goose the amount of sugar in their dishes. Ime Thai restaurants are the worst for this but Korean food often comes with ingredients that contain a surprising amount of carbs.
I have had some success getting restaurants to substitute stirfried shredded cabbage for rice as a bed for the other ingredients (though others look at you like you just asked them to use cotton candy instead of rice or noodles). It is possible to order sashimi or sushi naruto style (a roll wrapped in cucumber rather than rice) though proteins like eel, fake crab, and tamago (egg) often have sweetened ingredients. Egg fu yung can be a decent choice if it doesn't come swimming in gravy.
A lot of places serve chicken wings (again, watch the sauces and the rubs and the battered wings; "buffalo wings" usually are pretty safe), you can always take the buns off a burger and add lettuce and tomato or pickles. Salads are usually good as long as the proteins are keto friendly, croutons are omitted, and dressings are served on the side. And places that serve breakfast all the time? They're great. Eggs and breakfast meat are pretty safe for keto eaters (though it's not like you can't make those easily enough at home).
