I always thought they meant the email used for the WoS custodial account. But if you create an alias for your Apple ID email, isn’t it technically the same email as your Apple ID?
Discussion
Yeah, there's ways to do that. Recently used it to send an email and had a scare cuz the hidden email was still listed on my sent mail copy that I would view on my end.
Not sure how to generate one on the fly but will look into it if needed.
You can easily spin up one in seconds with the protonpass app
Or with https://simplelogin.io if you’re not in the protonverse