Oh, PyOxidizer also ran into more general issues with the frozen importer in that it broke various importlib APIs. e.g. because the frozen importer only supports bytecode, you can't use .__loader__.get_source() to obtain the source of a module. This makes tracebacks more opaque and breaks legitimate API consumers relying on these importlib interfaces.

The fundamental limitations with the frozen importer are why I implemented my own meta path importer (implemented in pure Rust), which is more fully featured, like the PathFinder importer that most people rely on today. That importer is available on PyPI (https://pypi.org/project/oxidized-importer/) and has its own API to facilitate PyOxidizer-like functionality (https://pyoxidizer.readthedocs.io/en/stable/oxidized_importer.html) if anyone wants to experiment with it.