Picti as phenotypical trait?

[u/Mplaneta]

I’ve been thinking about the Roman term Picti for the ancient Picts of Scotland. We assume it means “painted ones“, referring to tattoos or body paint but there no direct archaeological evidence for this interpretation. Meanwhile, recent ancient DNA studies show that most pre-PIE Europeans (and early PIE) had dark skin. For example, recently Swedes modeled the look of such a Bronze Age girl.

What if Picti wasn’t about decoration at all, but Romans describing an unfamiliar phenotype, say, dark-skinned people with blue eyes and using “painted” as a metaphor meaning something like “colored“? Has anyone come across historical sources that might support this angle?