pinentry-qt4 is long obsolete, but confusingly shows up if Qt5 is installed, and there ought to be an entry for pinentry-fltk (since >=app-crypt/pinentry-1.1.0-r2).
pinentry-qt4 was the symlink from pinentry-qt (which was built upon the USE=qt5 selected in pinentry, I've pointhed pinentry-qt to the pinentry-qt5 symlink (leaving a room for qt6), as for fltk, it is really pointless, I have disabled its support.