Those mobo holes look metal-lined, like they're attached to PCB ground plane and are meant to have metal screws and metal standoffs and metal chassis, lol. I'm a firm believer in having proper electrical contacts, lol, at least on high-spec or overclocked hardware.

But you can probably use longer screws if the existing ones aren't long enough to tap through your M.2 plastic to the mobo to the standoffs. Shouldn't cause any electrical faults. You might need to be careful about mechanical stress, don't overtighten the screw and crack your mobo PCBs.