Turns out this is covered in the readme: libsqlite is a fork (so, presumably C) while turso database is a rust rewrite.

Good luck to the friends at Turso!

Being written in Rust it's not even a good libc-less drop in choice for a language like Go?

I’d be more excited and imagine it would be more marketable if it focused instead on being simply an embedded sql db that allowed multiple writers (for example), or some other use case where SQLite falls short. DuckDB is an example- SQLite but for olap.