I mean it was famously tested in 2015 after the San Bernardino attack. Apple didn’t back down [1] and later sued the company who sold the zero-day to the govt to unlock the phone [2].
That's an ordinary subpoena and that data is not being specially collected and not e2ee encrypted. Has nothing to do with the guarantee in this article.
[1] https://en.m.wikipedia.org/wiki/Apple%E2%80%93FBI_encryption...
[2] https://www.washingtonpost.com/technology/2021/04/14/azimuth...