What is the smallest possible board to run OpenCV on?

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hello there

So I am working on a little project right now where I need the smallest possible board to run OpenCV on.

I already bought and tested an LicheePi Zero but it is so poorly documented, I didn't even get the camera to work.

The board should be around 35mm x 35mm to 50mm x 50mm. I also tought about the Lichee Pi nano. But as already with the Zero the Docs arent very helpful to me.

I am just starting with CV so a little bit of an advice would be helpful. And if you need additional information on the project or what are I am trying to achieve, I will provide it to you.

kind regards, SL7