Win32 was not removed from Windows RT, but your access to it (if your name wasn't "Microsoft"; because that low-level access was reportedly how they got Office on it) was.
And because of Secure Boot, which (unlike x86, for now) is mandated enabled for Windows on ARM systems, you had to wait for an unpatchable security hole in the booting process (which, while it exists, wasn't relevant until past the end of the Surface RT's lifecycle), you couldn't run full Windows 8 or a tablet-first Linux distro.
It's not mandated on for the newer Windows on Arm64 systems, but is configurable there.
Windows RT was just Windows 8 with a locked code signing policy, yup. And yes, Office on Windows RT was Win32, as were File Explorer, MMC, ... it's just recompiled Win8 after all.
So if you wanted an "unlocked" windows RT, couldn't you just have run windows 8?