incandescent bulbs put out a ton of infrared.
a green incandescent bulb can be used during dark period without causing any photoperiod interruption. I learned this from greenhouses and light dep grows.
I water my plants during dark period with green incandescent lights.
Amber tint also works for the same purpose in my opinion, I have a gooseneck lamp with an amber bulb that I use while watering when I need extra light or need to see the plants with more accurate color.
It might be effective for the same use as these expensive far red fixtures. And if you didn’t want any light that is “visible” to the plants, use a green tinted bulb.
I think it’s worth a shot. But you would need to test it out, and probably couldn’t verify that it is comparable to the led fixtures without a comparison grow to be sure.
Based on my experience watering during dark period every night with incandescent lights, it certainly can’t do any harm.