Well in that context TSMC N4P tells you no more information than 4-nm does.

No information, but at least it doesn't mislead into thinking there are 4nm transistors, or transistor gates, or some discrete feature of any sort that's that small.

Are transistors per square mm a better metric ?

I won’t be surprised if the US plants started referring to the 4NM nodes in their imperial form (1.575 × 10-7”)

Angstroms aren’t imperial, but they are non-SI, so if we want to be petty they’d probably be the way to go.

Scientific notation would be to logical. Instead they'll make a new tiny unit that subdivides the inch into 1/81975489347.7 of an inch.

God yes.

As such I’m going to assume it’s the least impressive variant of 4NM.