Uniform
Uniform is a multi purpose, art focused data editor.
With Uniform you can use the exact same toolkit for creating high poly sculpts, low poly models with textures, normal maps, PBR painting and layering, 2D images and final renders. No modes, no different tools and settings for different object types. Uniform allows you to use the exact same paint brush to paint on a high poly mesh or on a pixel art image.
You can find more information about Uniform in the Uniform Introduction.
Downloads
You can get Uniform for iPad on the App Store.
Tutorials
You can follow this tutorial series to learn how to use Uniform and get an overview of its main features.