You can still get the key from huami servers and say good by to xiaomi scientists checking your data.

Can you do that without installing their app which will have access to your contacts and location upon first access?

Well, you need to install the app at least once, no need to give it full permissions. You might also use a burner device. Once your device is paired, you can remove the app and go to fetch the key.

Search for huami-token on github or for Huafetcher (android version of the same) on Codeberg.

And read our wiki

Disclaimer: I did the Kivy wrapping of huami-token for Android.