How many times do you imagine you’ll be re-initializing your Vault cluster? This should only be a once in a life time operation. There is no point in automating it. Yes, in every enterprise that I’ve been a part of you trigger an action for a human to do the init and secure the environment.
If you’re using a lab env, then you can set what you want your root key to be, set your unseal key count to 1 and throw it away, every restart is a new vault.