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

https://github.com/ahesford/void-packages opencv4
https://github.com/void-linux/void-packages/pull/23371

opencv4: allow python subpackage to cross build
Split from #23370 to avoid CI timeouts.

A patch file from https://github.com/void-linux/void-packages/pull/23371.patch is attached