I don't know about every macbook, but I just tried this twice on my 2019 macbook pro and pressing any key on the keyboard (or at least the 2 keys I tried, "f" and "8") will power it on when it is powered off (yes, fully shut down, not asleep). Based on some quick googling, this still appears to be the case for M-series macbooks.

Since the introduction of M1 series, there is no permanent shutdown. Even after full shutdown, any keypress on keyboard will power up the system.

My M1 Macbook Pro turns on (after being fully shut down) by keypress.

That’s a pretty wild definition of “fully shut down” that manufacturers (not just Apple) are pushing. When my device is shut down, I expect it to be fully de-energized and drawing zero current. How can a keyboard action re-apply power if the button itself is not completing the power circuit?

This is one of the reasons I’ve started putting all of my devices on power strips with physical switches that de-energize the AC mains. You can’t even trust devices to power off when they say they are off.

The number of devices in your home that draw current when they are “off” is too damn high.