We should fix this in time for the next pre-release of Go 1.16. If you'd like, you can wait until then, but you certainly don't have to. This issue affects only the installer, the actual Go distribution is already built for ARM64. You can also use the go1.16beta1.darwin-arm64.tar.gz archive to avoid having to install Rosetta 2.
I tested the change described in #43422 (comment) by making use of pkgutil --expand and pkgutil --flatten to adjust the distribution XML:
$ pkgutil --expand go1.16rc1.darwin-arm64.pkg out
$ $EDITOR out/Distribution # set hostArchitectures="arm64" in options
$ pkgutil --flatten out go1.16rc1.darwin-arm64-edited.pkg
(This process strips the signing, but that's not a problem for the purpose of testing the change described here.)
I tested this on a Mac without Rosetta 2 installed (thanks @cagedmantis). Prior to explicitly setting hostArchitectures, Rosetta 2 was required and the installer would not proceed without it. After setting it, Go was successfully installed without Rosetta 2.
It also had the added benefit of reporting "Go can't be installed on this computer." if the ARM64 installer is opened on an Intel-based Mac (previously, the ARM64 installer would run without letting the user know it's the wrong architecture, but then the installed distribution wouldn't work because Intel-based Macs can't run arm64 binaries).
We've updated our release process to apply this change, so the next Go 1.16 release will have this fix. Thanks again for the report. Closing.
@ifamakes I've checked the Distribution file in go1.17.darwin-arm64.pkg, and it still has hostArchitectures="arm64" set, so that hasn't regressed on our side.
Since this issue has been closed for a good while, I think we should treat this as a possible new problem. Can you please file a new issue that references this one, and provide more information, such as what macOS version you've tested with. Thank you.