"Fiber from food" seems good enough. It's hard not to fibermax without incidentally improving your diet substantially. For example, beans are one of the best and easiest sources of it.

Splitting hairs beyond that, like insoluble and soluble, is the kind of thing that just confuses and intimidates people about nutrition advice.

It's a bridge you can cross once everyone is eating 50g+ of fiber per day, has chiseled physiques, and are looking to min/max.