Created attachment 699300 [details] build.log dev-python/cffi-1.14.4 CHOST=armv7a-unknown-linux-gnueabihf Looks like #582130
Created attachment 699303 [details] armv7a-unknown-linux-gnueabihf-emerge --info
Python doesn't really support cross atm, so I honestly doubt there's a way to get this to work without major changes.
I did have it working in https://github.com/gentoo/gentoo/pull/9822 but the eclass have changed a lot since then and it needed a major rework anyway.
Ebuild now uses PEP517 and mgorny recently added cross-compile support to gpep517. This should work now.