Hairball preventatives for vegan cats?

[u/JayNetworks]

(Let's skip the whole can cats eat an all plant/vegan diet thing and assume for this question that these two cats are doing just fine long-term on their all plant commercial kibble diet.)

We have two vegan cats. One almost never has hairballs. Her sister/littermate has frequent hairballs...and usually on the bed or couch of course.

Does anyone know any hairball treatment products that are actually vegan with no animal products like chicken flavor or gelatin? There are some we've found that are close, but have things like natural chicken flavor or by-products of gelatin.

Ideas or brands? Our vet says that just using most oils added to their food isn't a good idea in cats. (Specifically she said: In reviewing the veterinary literature and search boards for information on natural oils and hairballs-coconut oil, olive oil, canola oil, and sesame oil are sources of medium chain triglycerides which have been associated with hepatic lipidosis in cats, so I would recommend avoiding these.)

[u/Richyrich619]

Everywhere ive seen says to brush them often , also pumpkin

[u/mister__cow]

If you're in the US or Canada, Nature's Hug makes a hairball formula