I just bought some 1600-1800k 'yellow' led. I bought it, curious about the specification of this one as having a color temperature rather than a wavelength. Upon inspection, it shows a wide hump, almost identical to the phosphor hump of any random 80 cri 2700k led lamp. For fun, i also bought a 590nm led.

The 1600-1800k LED appears to actually be a 'normal' phosphor led. When viewed under 395nm near UV, it lights up yellow. However, the pump diode radiation is 100% suppressed. It is actually there - if i get a true high quality spectroscope and put it right onto the LED itself, i can barely, very faintly perceive the slightest of blue lines after letting my eyes adjust to the dark. However, it completely disappears into the noise floor with the spectrometer (attachment 1).

The color is reminiscent of SON HPS lamps. There is distinguishable color rendering. The 'shoulder' is wide enough to allow for some green recognition. However, the blue is suppressed to the degree that although SON will give you some blue, this will not. For the true SON-like color you will need to blend a very tiny amount of blue into it, also to increase color temperature from 1600-1800 to 1900-2000k.

I am convinced this is the type of LED used in the Poelenburg neighborhood of Zaandam. For some reason, that neighborhood is partially lit with yellow LEDs along the main roads, with some green and red rendering. No clue why they chose for this and didn't stick to 2700k which the neighborhood has on the other side. And then 3000k in the residential streets, where 2700k would be way more appropriate and 3000k on the main roads...

On the other hand, the yellow 595nm LED (attachment 2) is fully monochrome. It is essentially identical to SOX low pressure sodium. The peak is very narrow. Not as narrow as from sodium, but narrow enough for it to make no difference at all.

I bought these from https://nl.aliexpress.com/store/2335145?spm=a2g0o.detail.0.0.1248uweuuweumr - i was stupid and didn't order the very rare teal leds (actual teal, not phosphor converted!) they sell.