Questions about LLM app development | I will not promote

Hello everyone! We are a team focusing on building developer tools for LLM-application developers. I have a few questions related to building LLM-backed apps, and the specific challenges you encounter. <i will not promote> What do you guys think about a centralized RAG where users sign in to your app with a specific Oauth2 identity provider (like google sign in button) and you can access / prompt with the user's whole data across other apps? What about edge deployments. Do you think it would be useful to have fine-tuned smaller models that you can run on browsers or mobile devices and you can call these instead of LLM providers? I thought this would be good for cost cutting but I'd love to hear your opinion? What are some specific challenges you encounter when building an LLM-backed app as opposed to a traditional app without LLMs? Sorry if this is not the right place to post it :)