Create a riscv64 builder
Since there seems to be a general consensus that having Alpine 3.15 deliver riscv64 packages is a good idea, we need to start preparing infrastructure for it. So far, all of my work on riscv64 port has been done with qemu-user-static in a OCI container and that works really well so far (especially when run on a 32-core beefy x86 box). The other alternative is a full qemu-system-riscv64 VM that can be done pretty easily as well.
Personally, I'm running my automation around this on GitHub's Actions (using their x86 ubuntu-latest box). This may be a useful starting point for some: https://github.com/lf-edge/eve/blob/master/.github/workflows/publish.yml#L27
Also, here's how I boostrapped a build container by simply running
docker build -t riscv64 https://github.com/lf-edge/eve/blob/master/build-tools/src/scripts/Dockerfile.alpine.bootstrap
Again could be useful.