For deployments using Argo, yea that's pretty much it. You can set it to automatically deploy to your target environment as soon as it detects changes to your k8s mainfests, or you can require a manual "approve" step which is a push of a button for configs that are out of sync with what is applied to k8s.
For rollbacks, you have a button in argo that lists previous deployments and you can just choose which previous deployment you want to go back to. It works pretty well those (thankfully few) times i have had to rollback any deployments.
For automated testing the argo-workflows project is amazing and worth looking into.
I think when you look at the entire argo suite you start seeing something that could really disrupt the way we use products like gitlab, particularly for startups.
For rollbacks, you have a button in argo that lists previous deployments and you can just choose which previous deployment you want to go back to. It works pretty well those (thankfully few) times i have had to rollback any deployments.