Vault on MacOS without dev server mode
Considering Hashicorp's recent decision to not participate in the open source or free software movements I don't think it will be beneficial to contribute improvements, such as this project. I'm sure they would be happy to pay for an engineer to build this. The only way that would happen is if one of the product managers felt like it would be an improvemenet for the product, so I'm not holding my breath.
The Hashicorp vault formulae included with homebrew creates a MacOS service for vault. Sadly this service is running in dev mode and doesn't provide a basis for building something potentially production-worthy.