how do I spawn OS shaped message forms? (Tkinter alt. for RenPy?)

[SONTSE]

I need my project to create some message boxes
which must look like normal (error)message\notifications you expect from your os,
and exist (or pretend to) separately from renpy (eg. after renpy.quit() ).
It is for some erm... "breaking the fourth wall".

So far i figured out how would I do this in vanilla python with Tkinter,
but there's some sad info from other threads:

... some modules (like ... Tkinter) won't work at all.

so if I get it correctly and it is still the case, I think
I need either other GUI module which do work,
or any way to squish desired functionality out of default toolset.

Any help/advice appreciated. Thanks ahead!