There is a new pull request by sgn against master on the void-packages repository

https://github.com/sgn/void-packages build-help-split-devel
https://github.com/void-linux/void-packages/pull/21721

xbps-src: declarative split library and development file
@void-linux/pkg-committers 

A patch file from https://github.com/void-linux/void-packages/pull/21721.patch is attached