App updated! My little dude, Has put on clothes - No longer nude!

I greet everyone without a word. I am stepped on by strangers and loved ones alike. Those who use me the most rarely look me in the eye. Some see me as protection, others as an invitation. Treat me too kindly, and you might become me. What am I?

A tiny whisper on four small feet, In silence prowls where crumbs retreat. Or with a computer I'm not too bad, Leading your pointer on a pad.

Whole, I am close to you But lose one and I become a vicious demon Lose two and fight back Or else lose three and it's all over.

In citrus realms, I play a game, sweet yet sour, I stake my claim. A sunrise hue with a bitter bite, my giant kin keeps breakfast bright.