How is the OS loaded on mobile devices with x86 processors?

Question

Iron

Hello.
I dream of a tablet (and a smartphone) on which I could install a full-fledged desktop OS, the same arch.
But how is a normal OS installed instead of a bucket on them, and how is the OS loaded?
There through EFI loading is carried out, or through MBR? Those. connected the smart to the computer, marked out the partitions, mounted the partition and rolled the same arch through pacstrap? Or will you still understand the dick, as on devices with arm processors?