This is arguably the best free alternative for Nikon users. It is open-source, supports almost every Nikon DSLR/Z-series camera, and allows for remote triggering, live view, and advanced time-lapse settings. darktable (Windows/Mac/Linux):
Q: Are there any alternatives to Nikon Camera Control Pro 2? A: Yes, consider third-party software applications or Nikon's free software offerings. nikon camera control pro 2 product key free work