I've always viewed there as being a sort of inherent contradiction between chat search and document search. You can do either one well, but not both.
Although as far as I understand this approach of yours seems to still suffer from having to identify the most reliable source(s) to interrogate first... which is essentially The Problem™ of search and if you can do that well enough to make a conversational search engine give good answers, then you already do search way better than Google's ever done.
I think the search engine with citations is a great idea - you're grabbing onto a big trend while solving a clear, hugely-discussed problem (you can't trust LLMs to give truthful answers, and that's exacerbated by the fact that you can't see where their info is coming from). Hope it works out for you.
GP is responding to other naysayers without directly replying to them (:
And to be clear, I think going down the LLM rabbit-hole is absolutely the thing for them to do (see the quip about AI being their "core biz"), but you wonder why it wasn't them that came up with ChatGPT-like system in the first place, if disrupting is what's Neeva is about? Though, I don't think Neeva is out to disrupt Google Search when the differentiator is merely a different business model; I mean, per definition of the term as Christensen meant it [0], it is pretty hard to disrupt free.
[0] What is disruptive innovation (2016), https://archive.is/IzaKy (hbs.org)
iirc Neeva wasn't doing too flash back then.
Now, Neeva's playing in its own ballpark.