I needed a DIY stroboscope to troubleshoot my childhood Wii, which was outputting a ~2.5 Hz rolling picture, keeping me from opening the Wii settings and troubleshooting. The plan was to make a simple “web view” tool which could set a strobe rate to match the frequency of the image refresh issue, also allowing the user to adjust the frame offset to set the picture properly in frame. This would result in the rolling screen appearing stationary when viewed through the phone using the tool. This tool is very basic compared to an actual stroboscope, which uses flashing lights and dedicated hardware, but worked pretty well for me.
I should mention that this issue could almost certainly be solved by finding a TV compatible with the output or troubleshooting the Wii’s internals, but this was the approach I wanted to take.