Is it possible to append a post script to env while in a pre script?

I run a pre:script via platformio.ini and in the script itself I would like to append (dependend on a different configuration) a post:script.

I tried it with env.Append(EXTRA_SCRIPTS=[post:myScript.py]) but without success.
Later I found the corresponding code in the core:

And it seems by using GetExtraScripts() it will only consider the extra_scripts in the platformio.ini

Is there any other chance to do it?