Hi,
You can rest assured—you can use UEFI on this laptop even though the integrated GPU indicates it isn't supported; that refers to the boot mode itself.
However, when you enable UEFI boot, Windows needs to be set up for UEFI mode. I believe yours is currently in Legacy mode, so enabling UEFI might prevent Windows 10 from booting. Check if your drive (PO:ST9235) still appears in the boot list after enabling it, since it is a Legacy boot device.
If it doesn't appear, simply disable UEFI Boot in the BIOS again.
Thanks.