QGIS requires `qscintilla-python` which in turn requires `qscintilla`. Version 2.10.4 for the latter, seems not to be available.
See
emerge -av qgis
These are the packages that would be merged, in order:
Calculating dependencies... done!
emerge: there are no ebuilds to satisfy "~x11-libs/qscintilla-2.10.4:=".
(dependency required by "dev-python/qscintilla-python-2.10.4::python-modules-kit" [ebuild])
(dependency required by "sci-geosciences/qgis-9999::science-kit[python]" [ebuild])
(dependency required by "qgis" [argument])
This ebuild exists in the gentoo repository: https://git