@aeva That's what I do! Compile binpkgs on a modern (from 2013) PC and then install them on 20-year-old x86 hardware. Works great for me, though lack of SSE2 requires me to patch some softwares on my own, Gentoo didn't do it for me.
(But I can't help you with Mollytime because I've no idea what that is and it's not in the Gentoo repositories, sorry)