It also doesn’t have private CA or cert generation features, so if you need that then perhaps Vault or OpenBao would be a better fit. Though if you wanted to use EnvKey for simplicity and security reasons, you could potentially do your cert generation with openssl or another tool and then store the certs in EnvKey.
The featureset isn’t 1-to-1. EnvKey is more focused on config management and ease-of-use and not so much on slotting into more complex custom infra that needs eg a private CA. Though like I said it is quite flexible so you could make it fit into just about any system if you’re willing to do a bit of scripting.