WiFi is electromagnetic radiation, and penetrates walls. The standard frequency is 5 GHz. With harmonics, we should expect similar behavior from wavelengths that are some whole-number multiple of this frequency.
There are multiple such frequencies within the visible light spectrum, such as 500 THz (orange), but visible light doesn’t usually penetrate walls, it’s instead reflected or absorbed.
On the other end, we have X-rays, which are in the range of 3×10^(16) - 3×10^(19) Hz, which are used medically to see into the human body. There are likewise whole-number divisors, such as 200, which put a potential fundamental at around 600 THz (green). Yet, we generally can’t see through people using normal light. That’s why we use X-rays.
Now, this is all well and good, but it’s all purely academic, because the reason why you can’t use your infrared sensors to detect the color blue or purple is because the infrared sensors aren’t sensitive in that frequency, the same reason why you can’t use your blue cones to detect infrared.