He means no.
Windows on another drive will not boot on a Pi, neither will most Linux OS's.
Only kernels/OS compiled for ARMv6/7/8 will boot. 7/8 won't boot on a ARMv6.
Could a Pi use QEMU and boot another OS from the drive?
Er maybe. I would not like to try on any except a Pi 3.
Boot an external 64bit x86 OS on 32bit Raspbian QEMU, probably not.
Serious code fu needed.
Maybe one day/year/decade?
If you can do it, go to Cambridge and pick up your CS degree.
We will pester Eben until he agrees to present it to you.
Code guru's will name their children after you.
Statues will be erected in Roblox with your name on them.
Linus can retire?
Revisit this post when Pi's run 64bit OS's
I'm dancing on Rainbows.
Raspberries are not Apples or Oranges