Give the user some textual indication while a unpacking a onefile app

Is your feature request related to a problem? Please describe.

When running an onefile app, unpacking the file takes significate time and there is no indication to the user that something happens.

Describe the solution you'd like
When unpacking the files, pyinstaller's runtime will print a short message to the user, to indicate that the program is running and will be available soon. It can be a fixed pyinstaller text, can be user provided text, can be a progress animation, or anything else that will not leave the user wondering if the program actually runs.

Describe alternatives you've considered
Pyinstaller supports flash image but I am using my app in a text only interface. There is also the option of not user onefile in the first place but this will make it more difficult to distribute binaries.

Additional context
None

No file or test is named. Start by locating the onefile unpacking runtime entry point and reviewing how console output is handled during startup; define the intended textual indication and verify it appears while unpacking without disrupting application output.