Is no one aware of Fedora Media Writer? It’s FOSS and the most trustworthy ISO burning software in existence. It’s only issue is that its named as if it is written only for producing Fedora bootable media. It works for everything.

GrapheneOS is both secure and private. It also supports hardware based attestation (No need for SafetyNet). It’s just that mediocre people who develop these apps do not wish to support freedom respecting platforms.

Your dumb phone is much insecure than a smartphone which has GrapheneOS or LineageOS. Your dumb phone certainly lacks secure 4G or 5G communication, cannot use e2e encrypted messaging platforms and cannot update firmware in case of security bugs.

How would Signal help with zero days?

Did you even read the article? 0-day vulnerabilities are not unique to WhatsApp. Even Signal can be exploited given it’s complexity.

SimpleX is not a Signal fork. It is it’s own protocol, service and app. It just utilizes Signal protocol for encryption like every good e2e encrypted messenger out there.

SimpleX allows anonymous identity, federation between servers and still a good UX.