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

https://github.com/ackalker/void-packages efibootmgr-add-part-option
https://github.com/void-linux/void-packages/pull/12899

efibootmgr: add option to set partition number of EFI partition
This is useful when ESP is not the first partition, for instance if it
is added after some existing partitions during switch from BIOS to
UEFI boot.

A patch file from https://github.com/void-linux/void-packages/pull/12899.patch is attached