R&D Cannabis Plant Steering Application

https://unitronicsplc.com/ might be fairly cheap, I haven't used them for any SCADA but standalone they worked alright.

For lighting, and depending on the hardware, you can PWM a digital output to control power to the light. That's how arduino makes analog output.

Would not be prudent to use relays for high rate switching. But a transistor output won't care.

Send samples my way...