Most of the hardware remains the same, however, antennas and chipsets do differ, so the motherboard and component placement won't fit (even if it were possible to 'plug and play' a different chipset onto it). It's not just 'an LTE chip and antenna' that needs to be added, it's a whole lot more.
Thank you for the answer.
Looks like need to buy a LTE tablet.
Or you can just buy an LTE router and connect your tablet to that.
Or use my smartphone.