The allow list signals that any file within a package (including outside of it's lib/) may use the non-nullable experiment. This is working correctly in the CFE - the code is parsed as opted in.

This is not working correctly to choose whether to run with sound null safety or not. The intended behavior is that if the entrypoint library is opted in, then run with sound null safety. This was the behavior before. With the latest dev SDK the actual behavior is that --enable-experiment=non-nullable is still required.