They (PyBikes, the backend of citybik.es) do seem to have some Nextbike cities. If your city is missing, you can file an issue to have it added. It's probably trivial for them to add another city if they already have code to read the Nextbike API.

However, if with Nextbike, you need an app to unlock the bike or something, then it's a way different problem and out of scope for me. I'd only do the display of stations on a map and their status, which is a common enough thing that can be done globally.