Apple toolchain not working

Is there any working example using the apple toolchains? I converted a buck project to buck2 but I'm running into the following error when just trying to build a simple `apple_library` target:
` 1: Error looking up configured node none//buck2/platform/toolchain:apple-default (prelude//platforms:default#213ed1b7ab869379) (prelude//platforms:default#213ed1b7ab869379)` (my `.buckconfig` aliases `fbsource` to `none`).

Does the apple toolchain work at all for non-FB developers?

Start with the `.buckconfig` aliases and the simple `apple_library` target described in the report, then reproduce the build and trace the lookup for `buck2/platform/toolchain:apple-default`. Done means a non-FB developer can build the example successfully with the Apple toolchain and the reported configured-node error no longer occurs.

Written by the indexing model from the issue text.