You definitely want a thicker face if your planning a bunch of sanding.
But as far as strength goes, any 3/4 plywood will hold onto a wall. Voids or not.
Matter of fact, the cabinets I pulled from the house Im renovating used simple Douglas fir 3/4 plywood. They were totally custom built to the kitchen, no standard sizes. Very well made. I really liked them, but the layout of the kitchen just did not work, so they had to go.
It took me a while to get the wall cabinets down, cause I wanted to save them.
I removed every screw and nail I could find. But turned out I missed a single nail. It took a 6 ft pry bar and a hell of alot of strain to get it to come down.
That when it finally came down was still completely intact.
I ended up cutting up the old cabinets to use as drawers for a work bench. This is one of them. Its holding no less then 100 lbs of hardware plus its own weight, and has been for 3 months as is.
And it served the previous owner for I assume at least 20 years.
Point is, I dont think its that critical. Get the best material you can get within normal channels, and you will be good to go. And use cabinet screws with a washer head, or regular screws with standard washers, screwed into the studs, and that cabinet will be solid.
I just counted - 6 plys and there are voids here and there.
Sent from my SM-G930V using Tapatalk