Based on Nikon’s response reported by the asker, no—the Z6/Z7 cannot fully disable those systems in the way you’re hoping for during timelapse shooting. Even if you turn off or avoid using the EVF and rear LCD, the camera does not offer a mode that shuts down the sensor and related mirrorless operating overhead simply because you’re shooting manually without AF or metering.

So in practice, you should not expect DSLR-like battery savings from disabling those functions on the Z6/Z7 for timelapse work. Nikon’s recommendation was to use external power, such as a wall adapter, for long runs.

For remote shooting where mains power isn’t available, that implies planning around spare batteries or a compatible external battery power solution rather than relying on menu settings to significantly reduce consumption.