4 years ago I was active on this solution and I found only server-class machine has that auto-power-on, as of today my laptop and desktop still do not have that, it used to be a server or workstation feature only, did something change? google showed a few servers at the top still.
Every motherboard I've used to build systems with has plenty of options in the firmware, APM being among the most user obvious. Integrated systems like laptops? Not so much.