We have a similar no dependency philosophy

SQLite already does this with its VFS layer. You hand it the OS functions it needs instead of it grabbing them, etc.

You could look at going straight to syscalls, mesa would be a rewrite nightmare

I went zero-dependency on a production CMS. Rust, no framework, no external crates beyond argon2 for password hashing. Running live on client sites. The hard part wasn't building it, it was accepting that everything you reach for is pulling glibc or similar assumptions back in through the side door. SQLite's VFS model is the right pattern. More things should work that way.