Not sure a blowgun would work from a moving platform like that. Yeah, yeah, don't inject realism and all that, but, I'm just thinking that a blowgun dart would be extremely short range with the wind like that. Now, thrown darts, that I could easily see. Thrown darts are closer to lawn darts than what you throw in the pub. Halflings carrying around bandoliers of throwing darts and bundles of javelins to fire from bees would work pretty well I think.
It would be an interesting niche for halflings really. Just lean really hard into the whole farming/husbandry aspect that's already there. If you're a group that is specialized in farming, you're going to utilize the things that nature provides and, in D&D Land, nature provides all sorts of really cool stuff that could be used. Fire Beetles would be a fantastic food source as well as a great light source. Very useful if we live in sod houses where fire is a real problem - carbon monoxide poisoning due to poor ventillation. Sod houses aren't exactly the most comfortable things to live in. Giant bees. Goats and war goats. I could see goats being more useful than ponies anyway. And, again, the fact that there's lots of medium flying animals - even normal vultures are considered medium in D&D, it would be fairly easy for halflings to rule the skies (although vulture riding halflings is a kind of weird image.)
Then again, I've always thought that the Monster Manual should be better integrated into D&D settings. There's all these easily exploitable resources there that never seem to make their way into settings or adventures.
Now I want to make a vulture riding halfling warlock.