Hi all, I've been doing this for a while now and it works well. I have a Sony Xperia z5, though my old z1 worked just as well. Checking my wife's iPhone. The positioning isn't as accurate on Google maps and the apple version of Google maps also has less functions, so I'd only recommend this on an android phone. I've been downloading offline map areas to the phone, then dropping the pin and labelling useful locations like funghi spots deep in the forests. Then I've tested then months later and the dropped pin is dead on location. If you're logged into your Gmail account, you can also see them on your main computer.