>It wasn’t just an app, Encrochat sold a modified android phone that had its camera and GPS physically removed

I doubt that provides significant value. Cameras aren't too hard to disable yourself, just use black tape. They probably didn't disable to microphones, which arguably provide at least more valuable information than a camera. They removed the GPS module, but you can probably get the same info with better accuracy by using wifi + cell phone signals. All in all, I think those "features" are just there to make criminals feel better.

But it’s verifiable for your counterparty. If you’re on Encrochat you know that your counterparty has no GPS in their phone.

But what's the threat model here? That your counterparty's phone has been compromised? In that case they can be leaking location through wifi/cell signals as mentioned earlier. There's also nothing preventing the counterparty from carrying a gps-enabled phone with him, which would be trivially linked to his Encrochat phone if he takes them both to the same locations.