That's debatable. AFAIK in EU law you still have warranty on the parts of the device that aren't affected / effected by the modification you make. If you manage to break e.g. the headset socket, that will most likely have no effect on the display, so the display is still under warranty. If you change the OS on your laptop, you will of course lose support on the OS, but if suddenly the keyboard stops working, even in BIOS, that would still be covered.

I reckon the same applies here. Swapping out the OS, also given that is an explicit option for these devices, should have no influence on the warranty on the hardware. You might lose factory warranty, but in EU law, the shop were you bought it is responsible for warranty anyway.