Yes, it was marketed in the dark web marketplaces as “the phone for criminals”
That app could run only on a special custom ROM. It was a dedicated phone, a Google pixel 4a with locked bootloader and a custom ROM that exclusively allowed to communicate with other anom users. You don’t buy a $2000 phone that could only communicate with other $2000 phones if you don’t have something to hide.
It might have happened that maybe a millionaire with disposable income bought a set to talk with his secret girl affair but those were definitely the minority