There are some alternatives that are absolutely more secure. Now the trade off might not what you want, but the iPhone and iOS isn't the most secure smart phone available.
https://www.silentcircle.com/products-and-solutions/devices/
Probably, but silent circle isn’t one of them. Silent circle is just a generic Chinese android phone without carrier bloatware. Instead, they ship a bunch of their own bloatware. They haven’t really made any fundamental improvements to security over what you can get with any other rootable android phone.
iOS has a generally much stronger hardware security model than Android, although it’s not perfect either, especially given that it’s closed source and not auditable.
I’m hopeful that Purism’s librem 5 cell phone will represent a substantive improvement in smartphone security. Runs standard Linux, isolated baseband, hardware kill switches, etc.
Things have not gotten better. So no, there are not alternatives that are “absolutely more secure.”
I think the phone is silly for other reasons, but that link is nonsense and largely unrelated to the discussion at hand.
https://www.bittium.com/BittiumToughMobile
It also comes with its own Secure Suite MDM and is not tied to any unwanted third party. It's quite expensive, though, and I have no first-hand experience of it. Just talked with some Bittium guys recently. Lots of former Nokians working there.