Hi, I'm wondering if it is possible to have swatches and brushes which can paint both diffuse, roughness and metallic channels at once.

Hi, that's unfortunately out of scope of the tool, but I'll add it to be planned for v2.0.0, thanks for the suggestion.

You can follow it here: https://github.com/orgs/PardallTools/projects/2

Thanks for considering this feature. This is what would make me switch from Blockbench to this addon.
Another addition on that is maybe it should be more generalized to not only PBR but any arbitrary channel/texture which can be input for Blender material nodes. So that it can be later wired to anything. The idea is to have several configurable inputs on a brush stroke.