I dont decline that, only saying the current Raspberry OS is a 32bit, which is the reason I am looking to the from-source installation.
For the presence of the missed file, I would expect the existing files will detected some how.
Code:
nico@raspi01:~/calibre$ dpkg -S QtCoremod.sip
pyqt6-dev: /usr/lib/python3/dist-packages/PyQt6/bindings/QtCore/QtCoremod.sip
nico@raspi01:~/calibre$ find /usr -name QtCoremod.sip
/usr/lib/python3/dist-packages/PyQt6/bindings/QtCore/QtCoremod.sip