Probably yes for basic triggering, but compatibility is not guaranteed. If the Sunpak NE-i’s trigger voltage is within what the Flashpoint/Godox receiver can safely handle, it should fire when connected through the receiver. In mixed-brand setups like this, the most reliable expectation is simple sync firing in manual mode.

TTL and other dedicated hot-shoe features may or may not work, because you’re combining older third-party gear with a different brand’s radio system. Even if the receiver physically fits and the flash fires, full feature support is uncertain.

So the practical answer is: manual off-camera triggering is likely possible, but verify the flash’s trigger voltage first and don’t assume full Nikon TTL compatibility through the Flashpoint receiver.