I always though discord was bad too, because all they clean is the username attached to your messages. So it can be very easy to know who sent them.

Very unorthadox suggestion, but those Vollaphones can come with Ubuntu Touch pre-installed. Best UI experience I had with a phone was an Ubuntu Touch. Pinephones also come with a Linux phone distro.

Sadly, we've lost Calyx till Febuary. Fairphone 5 with Calyx is the ultimate private phone. You can also get any Google device and flash Graphene.