Yes, it works. We have it running since ¾ year without any issues, you just need to activate the Elasticsearch-compatibility mode in OpenSearch:
I also managed to run the Zammad test suite (docker tests) with OpenSearch instead of ElasticSearch to verify the compatibility as much as possible. You can read the logs of the test here: docker: set user and password to admin by default · sebix/zammad@5401653 · GitHub