During hibernate (I don’t have a premium gad board to test out), does the power to the sockets get turned off?

Nope. Power is not controlled by micro.

Can you control it with a modified driver?

What are you trying to do?

Shut down sockets gracefully.
Remove power from sockets.
Wake up.
Restore power to sockets and initialize them again

It has to be part of the main board circuitry. Current Gadgeteer boards don’t support that.Sorry.

on current Gadgeteer modules,while ever power is applied to the power circuitry, there is power available to modules via the 3v3 and 5v rails.

You could design your own module that intercepted power lines to all downstream modules if you wanted. You could have as many in-out socket pairs as you wanted, that fed all the signals unaltered from the IN socket to the matching OUT socket, but was able to switch the power lines off when requested. You’d need a socket for controlling it.

Hmm… Not a bad idea. The only issue I see is to figure out what pin which is unused to signal power down. For a few of my modules I use all pins now.

Or I think I got what you said

Use one socket for controlling power. This connects to a PCB with N number of other sockets where all pins are wired in / out.

Power for all sockets are routed through eg a mosfet which is controlled through this one socket using one GPIO.