Hashicorp providing official binaries for arm64 since 0.8.4 release; I managed to build latest version from Gentoo tree (1.12.2) on my aarch64 vm without additional patches.
Sanity check failed: > app-admin/consul-1.12.2 > bdepend ~arm64 stable profile default/linux/arm64/17.0 (8 total) > dev-go/gox > bdepend ~arm64 dev profile default/linux/arm64/17.0/hardened/selinux (1 total) > dev-go/gox
arm64 done all arches done