There is an updated pull request by ahesford against master on the void-packages repository

https://github.com/ahesford/void-packages numpy-helper
https://github.com/void-linux/void-packages/pull/23515

[RFC] New numpy build_helper to support cross compilation
I plan on adding some packages that link against `python3-numpy` and require the same kinds of environment manipulations currently done in `python3-scipy` to support cross building. The new templates would be simplified if these manipulations were centralized in a build_helper, so here it is. `python3-scipy` has been reworked to take advantage of the new helper.

A patch file from https://github.com/void-linux/void-packages/pull/23515.patch is attached