[fjtktkgnfnr]

Those are always targeted extra hard since they tend to be used by criminals. See the recent "encrypted phones" (Encrochat, Anom, ...)

If you really care about security maybe it's better to get a really dumb 4G phone and share it's connection with a Linux small form tablet (but not running Android).

Of course, inconvenient as hell, but much more secure, especially since you are not running the iOS/Android mono-culture, so for anyone to target you it would require customized service.

[Ar-Curunir]

I don’t think ootb Linux is more secure than Android or iOS. You don’t even have simple sandboxing between apps.

[gjsman-1000]

But then you are vulnerable to physical attacks. You don't have hardware root of trust, so installing a PIN-guessing tool is easy. Extracting the encrypted data for attacking it on a computer outside the phone is also easy.

[jonfw]

So don't use a PIN?