Back in 2016 the picker was shipped with React Native.
When I started working with React Native again in September 2020 it had moved out of React Native into community repo, judging by the repo name: github.com/react-native-community/picker.
Reading the commit linked above I learned that the "react-native-community" org seems not to host repos anymore, which makes sense I think, otherwise everyone would want to be there which makes it kinda like another internet :). I am just not sure if this means that the component will be maintained more intensively than it was the case in the last years. Actually it sounds like a good open source project to help with, I felt the pain for a long time and if you browse the issues I feel that most of them are about styling the picker (on Android). Let's see if I get my android things solved and lets see then.