I recently put together a demo project that shows how to create fully interactive AI NPCs in Unreal Engine using speech recognition, AI chatbots, text-to-speech, and realistic lip synchronization. The entire system is built with Blueprints and works across Windows, Linux, Mac, iOS, and Android.
https://dev.epicgames.com/community/learning/tutorials/dOm7/building-a-complete-conversational-metahuman-ai-system-with-lip-sync-in-unreal-engine