The mecha musumes only make appearance as background mobs.
Here's one smol version mecha musume on her own.
Under that mask is a cute brat in need of correction💢💢

Small mecha musumes are more popular for tasks involving human interaction. They're smaller, lighter, tends to come with soft outer body like the arms with soft material, so they are much gentler with humans.
Larger sized mecha musumes could come with hard materials as the limbs if they need to perform rough jobs.