efivar-set
Setting efi variables from userspace without having to worry about UTF-16 conversion.
Set variable "meow" with gardenhouse uuid to value "nya":
efivar-set -e meow nya
Set variable "meow" with custom uuid to value read from file ./var:
efivar-set -e meow -u $(uuidgen) -f ./var
Source
efivar-set can be downloaded from https://git.pinkro.se/Rose/gardenhouse/efivar-set.git/about/
It's also mirrored to Codeberg where bugtracking is done.
A sys-apps/efivar-set port is available in the Gardenhouse portage overlay