Especially true for LEDs, tried that in the lab once with a flood light, got a few μA out of the LED shortened with the multimeter. Did that with 8th graders, we did other experiments mainly with pv, LEDs and bipolar transistors as well.

The logical question came up more than once: “can we use photovoltaic cells as a light?“. Pretty sure that‘ll work, too, but didn’t try because stuff was expensive then and we didn’t have any broken parts of cells at the time. They probably learned a few things on that day.

Steve Mould of Youtube fame did this:

Why all solar panels are secretly LEDs (and all LEDs are secretly solar panels) - https://www.youtube.com/watch?v=6WGKz2sUa0w

I did try to do that in 8th grade, it worked for a bit but it was quite dim and uneven.