The buns already contain so much sugar that they don't really apply.

I did keto for a while and looked at the nutritional information for those burgers, they're not really on the list unless you get them bun-free.

The veggie burgers when bun free do have carbs, but I'd consider them to be borderline okay at 6gm of sugar and non-fiber carbs (1gm of sugar) for 14gm of fat and 19gm of protein for a reasonably solid ratio of 6:33 or ~20%. It's not as good as bacon, but it's probably as good as beans...

Ref: https://faq.impossiblefoods.com/hc/en-us/articles/3600189392...

Just because this particular item isn't something for folks on a particular diet doesn't disprove the claim. It still is more accepting for people who have various dietary restrictions.

There are vegan ways to do that. No idea if they’re worthwhile, but they are possible.

Vegan keto is a pretty small intersection of the Venn diagram of foods, particularly if you're also avoiding refined seed oils.

I can’t imagine McDonald’s is a great option for that, anyway.

It's fine in a pinch having done keto for several years. But Five Guys or In & Out are better.