The thing to google is "therapeutic ketogenic diet". It's the super extreme form of keto, used in medical settings to treat things like epilepsy, rather than in casual settings in attempts to lose weight. It's been a while since I did reading on the topic, but IIRC, there is good evidence it's helpfully effective against some forms of cancer (but harmful against others, so research before diving in).

But yes. To answer your question, you do eat a lot of food that is 100% fat or darn close. You will see menus like "2 eggs and 2 tablespoons of butter". The vegetarian version will involve a lot of avocados and coconut oil. You don't have to eat it straight, and most meals involve combining a massive amount of fat with a small amount of protein or fiber or something.

This makes sense. The exact macros differ, I’m sure, but it seems reasonable that extreme medical situations could be helped by diets that otherwise aren’t the best for a healthy person

can't stand those filthy keto casuals /s

To be charitable, I suppose they mean getting your protein from whatever falls out of this high vegetable diet naturally.

You're right though, I think vegetables have more protein than people are led to believe, especially since the health/fitness industry make it seem like you need to be ever vigilant in getting your protein numbers up. Meanwhile, the average American accidentally eats far more than they need and certainly doesn't need to resort to supplementation.

They don't have complete amino acids profiles, so most plant based protein won't stimulate mtor and igf-1 like say... Whey protein, milk or a steak would.

I often hear that some vegetables (for example broccoli) have a lot of proteins but don't really believe it, as a vegan I find it hard to get protein.

Broccoli has only 3 grams of protein per 100g (and 7 of carbs), I don't think it is particularly high, and 1500 calories of broccoli would mean eating more than 4 kg of it.

You're quoting considerably more protein in broccoli than GP, and they certainly weren't suggesting eating it all in broccoli was actually a good idea.