At present, it is possible to emerge most packages in the Funtoo tree on a LibreSSL-based system. iputils is an exception here, as Funtoo's ebuild stands on a fork of Hideaki Yoshifuji's maintenance efforts as part of the USAGI/WIDE project (last release in 2012).
Building iputils against LibreSSL is successful on Gentoo, as David Heidelberg (okias) has taken it upon himself to fork Yoshifuji's work and become the de-facto maintainer. See his comments in the below Gentoo bug for more information.
https://bugs.gentoo.org/show_bug.cgi?id=503914
Could Funtoo switch back to using Gentoo's upstream ebuilds for iputils so that using LibreSSL on Funtoo is possible without an overlay?