Currently the example in python-any-r1 puts the PYTHON_DEPS variable in DEPEND. However, my best guess would be that this variable should go in BDEPEND, since the purpose of this class is to have a python interpreter available on and for the build host. The official python-guide also backs me up here: https://dev.gentoo.org/~mgorny/python-guide/any.html
I suppose the same applies to all eclasses. Will update them when I push the next update.
This seems to have been resolved in python-r1, python-single-r1 and python-any-r1. Can It be closed or is there anything else left?
Thanks for reminding me!