Physical device small enough to be quickly stolen: Not Secure. (this is self-evident: physical access to device is Game Over)
Low battery requires plugging in a cable to charge; the cable may be a surreptitiously-installed data cable. I do not trust the hardware or software stack that handles the data cable to be secure.
Many apps "require" silly amounts of permissions to the phone before they'll install. Apps' ability to read what's on screen, to be notified of clipboard changes, to listen to sounds; all when not even in the foreground. On my computer, I can easily check what apps and background services are running. Not so easily on a phone.
(this is self-evident: physical access to device is Game Over)
This is just totally not true.
I'd wager a fair sum that passwords stored on an iPhone, behind a decent layer of security, are entirely better protected from physical access than on any general-purpose computer.
Passwords stored on a general purpose computer, behind a decent layer of security, are entirely better protected from physical access than on any phone I've ever used.
As someone who uses this solution to your above-stated problem, I disagree with the assertion that phones are "Not Secure." Care to back that up?