I can only go off what I can find..
Osram doesn't even carry a deep red (660) or a deeper red (700nm)
CREE just started carrying "photo red".. i.e deep red..well a few years ago. still no cyan..
New Cree XP-E colors: Photo Red & Far Red - LEDSupply Blog
Part of the point is.. AFAICT no one manuf. makes ALL colors in all affordable packages..
Luxeon really has a complete lineup except affordable violets..
That said.. what "looks good" and what optimizes plant growth/watt are 2 somewhat opposing goals.
And the separate color emitter lights, though great for some things (flexibility in look i.e able to dim ind. colors for "effect". Better at covering large areas in close confinements i.e few inches off the top of anything) it is becoming less necessary.
As COB manuf. tackle the well known inherent drawbacks of white LED's and shifted to high CRI (which will roughly translate to more "full spectrum).
I see more of a future in building around a COB w/ some added accent chips than on overall single emitters.
Case in point would be to add, say violets to a COB center based on chip such as shown below:
These "luxury" COBS sell for about $2/watt, are not "the most" efficient chips (current small emitters and some less tailored COBS are exceeding 100-160 Lumens/watt)
Efficiency comes into play because part of the story is not just spectrum but gross amounts of photons..If one can get more photons out of a lesser 'balanced" light, in general it will be the one best for growth.
At least where look and function need to be considered.
This is just an opinion...
As to your orig. question, you pretty much know the correct thing re: ind. emitters.
As to a commercial product.. using "simple" 3W emitters isn't enough market separation (different than what the Chinese will bang out at 1/10 your cost..) for anything.
In my own dream of a both efficient and balanced light it would involve something like a large array of small violet based emitters in a 3:1(Yuji) ratio of high k and low k values on ind. channels.
at least for terrariums/aquarium type uses where lensing gets to be a problem..
5600K lensed COB of SORRA or Luminous Devices for "spots".
Again, not being negative, just trying to bring info and opinion..
Oh one more point of information. Some manuf are now making "dual" COB's w/ both warm and cool white on separate channels, allowing tailoring of output to ind. preferences..
They, unfortunately, are not the higher CRI (balanced) chips so still have some of the shortcomings of normal white LED's
Can't remember the name/company that manuf. them at this point.
Funny found one..
Alibaba has some manuf w/ "dual output" COBS if I remember correctly.