To prove that a single wavelength red led can indeed work in a tint mix: I tried mixing before with a 80cri 2700K led and a 640nm single wavelength led, and it worked very well: the red light lowers the CCT and at a certain mix ratio the CRI number was significantly higher than the 2700K led alone. I posted about it 3.5 years ago: pointless mods: a high CRI lighted tail (bonus: Cree XD16 test)
Lampman, I would like to test a board as well, if you have one left, will pay whatever is your costs. I can check output with my sphere and light quality with my spectrometer. I’m in the Netherlands.
I was in for an empty board as well long ago when things were still quiet in Belarus, I’m still interested in one as well.
I hope that you and your son are allowed out of your “prison” at some point and can build up some form of normal life.