Theres a long list of features we don't use. We primarily use Grafana for our dashboarding needs.

If I had to make a short list. Data streams, index lifecycle management and security on top of the OSS distribution of ES is all I need to view and manage K8S pod logs.

Worth noting that the developers of searchguard which the Opensearch / Opendistro security plugin is based on is also being sued by Elastic.