Ultrasuede is massively expensive and a specific brand-name. I'm wondering is generic microsuede might be usable as a stand-in? Something like this perhaps: https://www.fabricwholesaledirect.com/products/microsuede-fabric?variant=40532748566643&gclid=CjwKCAjwjMiiBhA4EiwAZe6jQ3G7P_xi1IolL6V6yO4P6...

Forearms are definitely the Shoretrooper/Tank Driver/R1 Trooper piece, so that's easy enough! I'm assuming the biceps are a new piece. Cool that they appear to have open backs, that will be splendidly comfy.