Icon is fine as long as you've got a tooltip explainer if the user decides to tap the icon, else it would just be another icon they're left to play guessing games about.

It's all about how important PoW is in the specific context, so why users should be interested in learning about it.

Writing it plain in a label, "XX-PoW", seems a good standard; you can play with font size and contrast to adjust the prominence.

a test reply