I was able to achieve this in GitLab with a CI/CD Component and an CI/CD inputs Array type.

Pipeline: bethomas/pipeline-experiments

Files:

• .gitlab-ci.yml:

include:
  - component: $CI_SERVER_FQDN/$CI_PROJECT_PATH/helloworld@$CI_COMMIT_SHA
    inputs:
      names: ["John", "Jane"]

• templates/helloworld.yml:

spec:
  inputs:
    names:
      description: Collection of names
      type: array
      default: []

---
component-job:
  script: echo $NAME
  parallel:
    matrix:
      - NAME: $[[ inputs.names ]]