How does Python LSP integration work?

My understanding is that Python LSP integration is supposed to be built using the `source-db` subtargets (and accompanying BXL scripts in the prelude), but I cannot find any mentions of "source db" in language server docs.
I'm very unfamiliar with the Python ecosystem, could somebody give me some pointers for where to start looking?

My understanding is that in the Bazel world, this is achieved by making venvs that contain both third-party and local dependencies. Is it similar in the Buck2 world?

I've looked at the git log for `prelude/python/sourcedb/ide.bxl`, but it's not quite enough context I believe.