Perhaps I'm in the minority, but seeing open-source used in the description made me think you were using or providing an openly available LLM in addition to the chat/search features. Instead it seems this is "merely" (I don't mean to undermine the level of effort involved) using OpenAI's GPT-4 API for its LLM.

This sort of reek of a growth mindset where you are using "open-source" for the purposes of looking cool and gaining users, but you are in fact trying to grow as quickly as possible to prove to investors that they should fund you for your next round.

I have no reason to believe that's the case for you in particular; just letting you know that some people may perceive things that way. Maybe you could make it clearer that it is a GPT-4 frontend of sorts?