Best option for automating outdoor lights for sunset?

Hi, my parents want their existing light fixtures to automatically turn on at when it gets dark outside. They were going to pay a guy like $70 to install sensors on each one, and we have a lot that arent all connected. One option I considered is maybe I can put a smart sensor and then we can put smart light switches that are activated by them using HA. I also want something that will work without internet, not something that relies on a server somewhere. But does anyone else have any better ideas or recommendations? Thanks.

I’m using a Pi 3 Model B with the 32 bit hass.io from https://www.home-assistant.io/hassio/installation/
Edit: I know it might not sound like the best idea, but the reason i want to use something with home assistant control, is because I want to do things one day such as blink the lights when a motion sensor detects someone after 11pm, plus i can control with google assistant when not home.

I use spotlights wired to a either z-wave plug or even zigbee inline switch. I then have the automation to turn on the lights 15 minutes after sunset and then off at a set time each night.

In terms of motion, you have a couple of options:

1 (easiest) get some outdoor motions sensors (again, here either zigbee or z-wave) and then build a motion trigger based on conditions. (This will obviously require a z-wave/zigbee stick or appropriate hub)

2 You could get some cameras setup and then connect them to motioneye, and then if motion is detected, fire a webhook to tun on the lights…

I considered that, but they said they don’t want it to turn on only at the time of sunset because where we live thunder storms are pretty much a weekly thing, and we have clouds. Good idea though. Do you know a light detector that will work with HA?
The ones we were going to have installed for $70 for set of lights looked like this: https://amzn.to/2KMq8ya
We would’ve had to pay like $600.
The closest outdoor light sensor with wifi was this Phillips hue one: https://amzn.to/2KU7k0f
The problem is I need a hue hub and I don’t know if there is a work around.