What's the problem this feature will solve?

I use tox to automate Cython PyRFC package builds for different platforms.

On Darwin platform both arm64 and x64 architectures are supported and some tox jobs should run on arm64 Darwin only.

I could not find a way to configure it in tox, only found this discussion #1149 about 32/64-bit selection.

Describe the solution you'd like

Would it be possible to provide tox job selection by architecture, for example:

platform = darwin
machine = arm64

As discussed here https://stackoverflow.com/questions/64044020/how-to-collect-current-architecture-in-python-3-in-a-way-that-is-portable-acros, platform.machine() looks reliable for this purpose?