I only have piCore 9.x on an RPi3 and piCore 11.x on an RPi4 to test and python works fine on both.
I downloaded the python3.6 extension from the piCore 10.x repo and it looks OK.
Do you get this: $ tce-load -i file
$ file /usr/local/bin/python3.6
ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), dynamically linked, interpreter /lib/ld-linux-armhf.so.3, for GNU/Linux 3.2.0, stripped