Migration off Base44

Anybody have any experience migrating an app off base44 and rebuilding a backend? I just got put onto this project at the company I’m interning for, they are building an internal app/tool for the company and I took over since I have software experience (system eng major + tons of projects).

Basically they want the AI tools and whatnot, but data privacy is a huge concern for them. So they want it not hosted on base44, I tried talking them into staying on it but it’s a non negotiable. The app is like 80 ish % developed, they’re still giving me new features for it, and we’re doing a total UI overhaul bc what I started with was vibe coded garbage. Gonna start proper user testing soon too. They want a built in AI agent that can help with various app functions, due to privacy I can’t share anything very specific but it’s basically a project management platform, plus other features for other departments. This won’t at all be an app for sale, specifically only an internal tool.

My question is mainly if anybody has experience with taking apps off the platform, building their own backend and then deploying. Planning on going supabase since I have experience with it, but any other suggestions would be helpful too. Like I said I have experience doing stuff like this from the ground up but wanted to know if anyone knows about stuff to look out for with base44 and how it’s backend works. Will be dev’ing the rest of the build out with Claude and Codex once removed from the platform, currently I have them auditing base44’s code and dialing prompts in for it so it gets stuff right. As of now I like the idea of going Vercel for deployment too, but we’re debating the option of going with local server hardware (I have experience as head IT) for privacy reasons.

Let me know if anyone’s got any advice for me, I’m a solo dev in a company of non software people so I’m a little on my own. Anything helps!