I got this from SwitchBot a few minutes ago:
Since the open API is not for every common user, so we would like to call it a beta version. Currently, it is not available.
Just check this information with our dev team. According to them, the open API for the Hub Mini will be released this summer. But the actual day will depend.
Your request has been forwarded to our dev team, which will speed up the process of them releasing it.
We are very sorry that you cannot be doing the open API as you wish right away, but we will try to make it quick.