Development for this project often needs to be done as close to the hardware as possible. Code changes typically require testing and validation on actual target hardware.
You can use whatever you are comfortable and productive in.
That might be nano, vim, neovim, Visual Studio Code, PyCharm, or something else entirely.
Note: nano, vi (mapped to vim), and vim are included on the WLAN Pi itself, making them useful for quick edits directly on the target device.
Need the choice made for you?
Try Visual Studio Code with the official Python extension. VS Code's Remote - SSH extension is particularly useful for developing directly on the WLAN Pi.
For those who prefer working entirely from the terminal, one effective setup used by a core developer is tmux + neovim + opencode.