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.

I’ve also seen it done using Dr. Breen in Garry’s Mod. They’ve just encouraged people to learn Blender or have your privacy violated.