Using ArgoCD together with Kapitan is actually pretty easy and only requires the kapitan binary in the argo-repo-server and a ConfigManagement plugin in ArgocD (https://argoproj.github.io/argo-cd/user-guide/config-management-plugins/)
configManagementPlugins: |
- name: kapitan
init:
command: [sh]
args: ["kapitan-base-compile.sh"]