This one is ridiculous. This should already exist. Until GitHub builds it, you can use GitHub Actions to kick your builds off but run them remotely on Earthly Cloud (https://earthly.dev/). Even the free tier includes arm64 remote runners.
Note: I work at Earthly, but I'm not wrong about this being a good, free, arm64-native workflow for GitHub Actions.
Note: I work at Earthly, but I'm not wrong about this being a good, free, arm64-native workflow for GitHub Actions.