So far as I'm aware, support for distributed builds in portage comes down to enabling `distcc` support - this this isn't entirely trivial and can have unexpected side-effects on non-identical host machines. What might be a valuable half-way towards this level of parallelisation, especially with reasonably affordable SBC systems being available, would be for portage - when building binary packages - to only use a single host for any given package, but to distribute the build of dependencies across all available machines. If the dependency graph was: $ emerge --tree pkg-a [ebuild N ] cat/pkg-a [ebuild N ] cat/pkg-b [ebuild N ] cat/pkg-c [ebuild N ] cat/pkg-d [ebuild N ] cat/pkg-e … then in innovation, one host could build `pkg-e` and as soon as the binary-package is committed three hosts could build `pkg-b`, `pkg-c`, and `pkg-d` in parallel, and then finally one host builds `pkg-a` once everything else is complete. Even better, this could potentially be managed entirely by binhost lock-files on a shared filesystem, removing the need for a network layer to be added - although the keyword/mask/USE flag state from the originating system would also likely have to be shared in order to reach a consistent state.
