Was the SurfaceRT an ARM device? I have one collecting dust, would be nice if it got an update

Yes. The RT devices ran ARM, which was one of the reasons for the locked down software policy (nothing else would run anyway).

Except that you were also denied much of the existing API and can only install software if you have a developer key from MS. I use my RT device for media playback in the car, but the windows-RT version of VLC hasn't been updated in years, and is somewhat buggy.

It also took VLC more than 2 years to develop and release the RT version. By the time it was released the market had already declared RT dead.

You might find that there are a lot of updates in the queue :-) . I dusted mine off a few months ago, and there were quite a number of them.

A qualified guess would be that you can just install it, because the bootloader is Microsoft signed so it would pass the secure boot check.

Edit: Apparently Surface 2 isn't AArch64, so probably not.

That assumes that:

(1) Microsoft makes generic install media available (rather than just device-specific restore media, for devices that ship with Windows 10 ARM), and

(2) Windows 10 ARM will run on ARMv7 devices, rather than being restricted to ARMv8 (AArch64) devices.

As far as i understand it, this needs an 64bit ARM SoC?