Earlier quoted context omitted.
...or Hamas just used modern encryption, which does work when implemented and used correctly. Merely using Signal consistently and correctly could very well be enough. There isn't an unlimited supply of over-the-air zero-day exploits.
Signal’s devs recommend that it be installed from the Play Store, and that is what the vast majority of people do. There has been heavy speculation that certain state actors are able to push a compromised Play Store update to users of interest. Moreover, the Signal board has been overhauled recently, Moxie left, and at least one new member has a US government background. It’s possible that the organization itself has…
I'm sure Hamas could figure out how to install Signal from clean APKs, or use something else entirely. They may be barbarians. But they're not stupid.
People forget that Gaza isn't a particularly poor country. It's GDP per capita is on par with neighboring Egypt, and only a little less than Ukraine. The supermajority of Gazan's have internet access too.