Arthur Whitney had a whole operating system, kOS, in a few hundred lines iirc (including bare metal storage drivers, screen drivers, file system and more), with a more-than-sql database in 200 lines and an editor in a few tens.

The magic — other than Arthur’s genius - was the programming language K (also designed and implemented by Arthur).

And from another direction, the STEPS project from Alan Kay did a metal-to-everything in 20K lines, including IIRC a paint program and word processor. They only counted lines you need to understand - e.g., it parses the TCP spec RFC to get all the structures and constants; the spec parser is included in the 20K count, but the TCP docs and the generated TCP code is not.