Today I found https://ciqual.anses.fr/, which is a searchable database of (average) nutritional values for a *wide* variety of ingredients, far more detailed than any nutrition label you might find on a product. Useful when you have specific nutrient restrictions or requirements!
Answers questions like "how much calcium do cashew nuts have" without having to wade through 50 pages of blogspam and LLM barf first.
On a related note, did you know that OpenFoodFacts has an ingredient volume estimator built in? If you add ingredients and nutritional values for a product to the database, then under 'ingredient analysis' you can see the volume (min/max) of each ingredient that it estimates and infers based on the available data, even when it is not explicitly listed on the packaging.
It's not perfect and it's always going to be an estimate, but it's very useful for answering questions like "does this contain a little bit or quite a lot?"
(Also please take a moment to contribute to OpenFoodFacts if you have some time, it's a very useful site, despite the very... suboptimal UI. Even just adding sharp pictures of product packaging is very helpful, then other people can extract the information from it)