With respect to threading: I have close to 0 experience.  I know that tkinter is supposed to be 'thread-safe' (Martin Loewis) and that people have real problems mixing threads with tkinter.  If you can create a minimal complete verifiable example (SO MCVE), try asking on python-list, or SO, so you can reach people who do know threading.

I suppose you can already guess my thought: for a first draft, block and let users wait.  For anything I have done with pip, that would not be very long.

I have done preliminary successful experiments with integrating asyncio and tkinter loop.  When I posted to the python-ideas thread on the subject, I got no response, so I moved on.  Perhaps I should work on it some more, but I am also busy with IDLE.