A difficult question I cannot answer with yes or no. But I do know that Inositol does have a measurable effect on the body. To my knowledge Erythrit is the only sweetener extant that does not show any effect. There is scientific literature on this on the internet, but it is not consolidated in one place.
Research suggests that inositol, or vitamin B8, may have various benefits, such as aiding people with mental health or metabolic conditions. Here are the benefits, side effects and dosages for inositol.
www.healthline.com
Technically a sugar but I suspect the quantities that you'd be taking it in mean that it isn't keto unfriendly?
Well, inositol is supposed to help with many conditions (according to some trials though, not widely accepted) but I think the amount must be high i.e. even 20g daily!