Injection is a powerful technique to control DC loads from an Arduino/ESP.
You can use a mini-buck converter as a DC power output that you can switch on-off and for which you can control the output voltage in a range of +20%-60%. up to 24V.
Yesterday, I made a stress test of my injection technique into the HW613 buck converter.
e.g. 10xHW813 buck converters
I had some worries about the current injection into the feedback loop reducing the stability of the converter.
So I tested it fooling it down from 7V to 3V and up from 7 to 9V and applying sudden load changes from 0 to 1 A.
In every case the output voltage remained perfectly stable within 1% tolerance.