There's a merged pull request on the void-packages repository

xbps-src: Add remove-obsoletes command
https://github.com/void-linux/void-packages/pull/30147

Description:
This cleans more than it probably should since it will clean several layers of nesting.  We could enable globstar and iterate over everything it finds, but I'm not particularly keen on this.

Open to changes on this, looking for feedback.