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

https://github.com/sgn/void-packages base-files-vkpurge-empty-boot
https://github.com/void-linux/void-packages/pull/20666

base-files: vkpurge: fix for empty /boot
On system with empty /boot (example: /boot on external device and not
mounted:
* `vkpurge list` reports `*`, which is incorrect, and
* `vkpurge rm all` run `remove_kernel` for all file names in $PWD,
  this will normally harmless except when efibootmgr is used and some
  files with special name, let's say "V" "o" "i" "d" in $PWD, then,
  efibootmgr will remove all boot entries.

Fix it by checking for `vmlinu[xz]-*` explicitly.
A sane system shouldn't have that file.

A patch file from https://github.com/void-linux/void-packages/pull/20666.patch is attached