My understanding is that modern mobile phone cameras do heaps of "stacking" across multiple axes focus, exposure, time etc to compose a photo that saves onto your phone. I believe its one of the reasons for the multiple cameras on most flagship phones, and then each of them might take many "photos" or runs of data from their sensors per "photo" you take. id love to see a good writeup of the process, but my gut says exactly what they do under the hood would be pretty "trade secret"ie.
Had a quick play with my iPhone 15. It doesn't give the sort of magnification you would need for insect close-ups. I will stick with my Nikon DSLR + 100mm macro lens!
Yeah it's far from being as good as a DLSR or mirrorless with a dedicated macro lens. Still, most people reading HN have one in their pocket and it can be a good test to see if you like the idea of macro. It does work with larger insects, on a pixel 10 pro my mantis fill most of the frame.
You can, depending on your definition of "useful". You can buy a cheap laser pointer, take out its lens, and put it over your camera lens. Tape it onto the lens for a temporary janky version or make a 3d-printed mount for something much better that you can easily take on/off.
I've personally found this little hack useful, but then again I don't have a DSLR and macro lens!