It's nearly impossible to find out. But if I trust corporations like Google not to exploit the possibilities, I wouldn't be looking for an open-source alternative to WhatsApp in the first place.
Eh, that’s exactly what it is currently advertised as.
A tool, supported by Snowden, to be used by journalists who are at risk of being under active surveillance by state actors.
That is the very definition of a TAO target.
And for non-TAO targets, WhatsApp is just as good as Signal – the users won’t read the source code anyway, and in both cases President Trump gets your social graph.
Aka NSA's "we really need to get access to this device and will fund diverting backbone traffic / writing firmware malware / whatever else we need to in order to get it" team(s).