I’m talking a $100 LED panel from Home Depot, not a full replacement to create a virtual skylight. Is it the appearance of sky or just the light? The light is easy, seeing sky (real or virtual) is hard.
I'm aware of those--I have one, except mine is 5x brighter. It's just not the same.
It doesn't cast the gorgeous shadows sunlight does. It creates glare that makes having the panel surface directly visible, no matter how obtuse the angle, unacceptable.
Sunlight's parallel rays make it so that it's not your window that's bright, it's the things that your window shines light on that are lit up. You can look at your window or the sky all day without any discomfort. And that's just not the case for traditional light panels.
Example: https://www.homedepot.com/p/JONATHAN-Y-2-ft-x-4-ft-Skylight-...